JOURNAL ON PROCESSING AND ENERGY IN AGRICULTURE
ČASOPIS ZA PROCESNU TEHNIKU I ENERGETIKU U POLJOPRIVREDI
Editor in Chief / Glavni i odgovorni urednik
Prof. dr Mirko Babić
Editors / Urednici
Prof. dr Ljiljana Babić
Prof. dr Anđelko Bajkin
For Publisher / Za izdavača
Danka Dujović, dipl.ing.
Technical secretary / Tehnički sekretar
Dr. Ivan Pavkov
Editorial Board
Dr. Mirko Babić, professor, Faculty of Agriculture,
Dr. Zuzana Hlaváčová, Slovak University of
Novi Sad, Serbia,
Agriculture in Nitra, Nitra, Slovak Republic,
Dr. Tajana Krička, professor, Faculty of Agronomy,
Dr. Costas Akritidis, professor emeritus, Aristotle
Zagreb, Croatia,
University, Thessaloniki, Greece,
Dr. Filip Kulić, professor, Faculty of Tehnical
Dr. Ljiljana Babić, professor, Faculty of Agriculture,
Science, Novi Sad, Serbia,
Novi Sad, Serbia,
Dr. Harris Lazarides, Aristotle University,
Dr. Anđelko Bajkin, professor, Faculty of Agriculture,
Thessaloniki, Greece,
Novi Sad, Serbia,
Dr. Jovanka Lević, Institute for Food Technology,
Dr. Costas Biliaderis, Aristotle University,
Novi Sad, Serbia,
Thessaloniki, Greece,
Dr. Mirjana Milošević, professor, Institute of Field
Dr. Miloš Tešić, professor, Faculty of Tehnical
and Vegetable Crops, Novi Sad, Serbia,
Science, Novi Sad, Serbia,
Dr. Vangelče Mitrevski, University "St. Kliment
Ohridski", Bitola, FYR Macedonia,
Dr. Janos Beke, professor, Szent István University,
Dr. Milica Radosavljević, Maize Research Institute,
Gödöllö, Hungary,
Zemun Polje, Belgrade-Zemun,
Dr. Marko Dalla Rosa, University of Bologna, Italy,
Dr. Branislav Karadžić, Faculty of Agriculture,
Dr. Mirjana Đurić, professor, Faculty of Technology,
Novi Sad, Serbia,
Novi Sad, Serbia,
Dr. Ivan Pavkov, Faculty of Agriculture, Novi Sad,
Dr. Richard Gladon, Iowa State University, USA,
Serbia.
JOURNAL ON PROCESSING AND ENERGY IN AGRICULTURE
Izdavač: Nacionalno društvo za procesnu tehniku i energetiku u poljoprivredi (bivše društvo YUPTEP), 21000 Novi
Sad, Trg Dositeja Obradovića 8. Suizdavač: Poljoprivredni fakultet, Novi Sad, Trg Dositeja Obradovića 8. tel :++381
(0)21 459 958; e-mail: [email protected]; Internet sajt: www.ptep.org.rs; Korektura: prof. dr Ljiljana Babić, prof. dr
Anđelko Bajkin; Dizajn časopisa: prof. dr Mirko Babić, Lektura: Aleksandar Jagrović; Prelom: Zoran Stamenković,
MSc i dr Ivan Pavkov, UDC brojevi: Slađana Beker; Štamparija: "Offsetprint", Novi Sad, Matice srpske 6. Tiraž:
250 primeraka; Godišnja pretplata: 1200 din (žiro račun: 340-4253-72, Erste banka, Novi Sad); Rešenjem
Ministarstva za informacije Republike Srbije, br. 651-105/97-03 od 6.2.1997, časopis je upisan u registar pod brojem
2307. Kategorija časopisa (2013): Vodeći časopis nacionalnog značaja – M51. Radovi iz časopisa nalaze se u
elektronskim bazama: SCIndeks i AGRIS (FAO).
CIP – Katalogizacija u publikaciji Biblioteka Matice srpske, Novi Sad
631.55/56:620.92
JOURNAL on processing and energy in agriculture = Časopis za procesnu tehniku i energetiku u poljoprivredi / editor in chief
Mirko Babić. – Vol. 14, no. 1 (2010) - .- Novi Sad : Nacionalno društvo za procesnu tehniku i energetiku u poljoprivredi, 2010-. –
Ilustr. ; 30 cm
Tromesečno. – Nastavak publikacije: PTEP - Časopis za procesnu tehniku i energetiku u poljoprivredi (1997-2009)
ISSN 1821-4487
COBISS.SR-ID 247980295
CONTENT / SADRŽAJ
Ljiljana BABIĆ
PLASMA APPLICATION FOR BIOMATERIALS PROCESSING /
PRIMENA PLAZME PRI DORADI BIOMATERIJALA .................................................................................................................. 95
Sanja OSTOJIĆ, Darko MICIĆ, Mirjana PAVLOVIĆ, Snežana ZLATANOVIĆ,
Olgica KOVAČEVIĆ, Branislav R. SIMONOVIĆ, Ljubinko LEVIĆ
THE GLASS TRANSITION OF OSMOTICALLY
DEHYDRATED PORK MEAT /
STAKLASTI PRELAZ OSMOTSKI DEHIDRIRANOG SVINJSKOG MESA .............................................................................. 100
Maša BUKUROV, Siniša BIKIĆ, Bojan MARKOVIĆ, Ivan PAVKOV, Milivoj RADOJČIN
DETERMINATION OF SOME PHYSICAL PROPERTIES OF BIOMASS FOR
THE PURPOSE OF PNEUMATIC TRANSPORT /
ODREĐIVANJE NEKIH FIZIČKIH SVOJSTAVA BIOMASE
ZA POTREBE PNEUMATSKOG TRANSPORTA ......................................................................................................................... 103
Aleksandra DIMITRIJEVIĆ, Anđelko BAJKIN, Slobodan BLAŽIN, Dragan BLAŽIN
UNIFORMITY OF AIR TEMPERATURE AND RELATIVE HUMIDITY INSIDE
AND OUTSIDE THE DIFFERENT TYPES OF GREENHOUSES /
DISTRIBUCIJA TEMPERATURE I RELATIVNE VLAŽNOSTI VAZDUHA
UNUTAR OBJEKATA ZAŠTIĆENOG PROSTORA RAZLIČITE KONSTRUKCIJE.................................................................. 107
Aca JOVANOVIĆ, Milada PEZO, Lato PEZO, Sanja STANOJLOVIĆ,Biljana LONČAR, Milica NIĆETIN, Ljubinko LEVIĆ
UTILIZATION OF SCREW CONVEYOR AS PRE-MIXER: DISCRETE ELEMENT MODEL /
KORIŠĆENJE PUŽNOG TRANSPORTERA KAO PREDMEŠAČA:MODEL DISKRETNIH ELEMENATA ............................ 111
Mirjana PAVLOVIĆ, Sanja OSTOJIĆ, Snežana ZLATANOVIĆ,
Dragana MITIĆ-ĆULAFIĆ, Olgica KOVAČEVIĆ, Darko MICIĆ
PHYSICOCHEMICAL CHARACTERICS OF SUGAR BEET MOLASSES USED AS THE MEDIUM FOR OSMOTIC
DEHYDRATION OF PORK MEAT / FIZIČKOHEMIJSKE KARAKTERISTIKE MELASE ŠEĆERNE REPE
KORIŠĆENE KAO MEDIJUM ZA OSMOTSKU DEHIDRACIJU SVINJSKOG MESA ............................................................. 115
Tatjana KULJANIN, Biljana LONČAR, Milica NIĆETIN, Vladimir FILIPOVIĆ, Violeta KNEŽEVIĆ, Jasna GRBIĆ
THE EFFECT OF CALCIUM SULPHATE, ALUMINIUM SULPHATE AND
POLYELECTROLYTE ON SEPARATION OF PECTIN FROM THE SUGAR BEET JUICE /
UTICAJ KALCIJUM SULFATA, ALUMINIJUM SULFATA I POLIELEKTROLITA NA
IZDVAJANJE PEKTINA SOKA ŠEĆERNE REPE ........................................................................................................................ 119
Violeta KNEŽEVIĆ, Biljana LONČAR, Milica NIĆETIN, Vladimir FILIPOVIĆ,
Lato PEZO, Tatjana KULJANIN, Ljubinko LEVIĆ
OSMOTIC TREATMENT OF NETTLE LEAVES IN TWO DIFERENT SOLUTIONS- MASS TRANSFER KINETICS /
OSMOTSKI TRETMAN LISTA KOPRIVE U DVA RAZLIČITA RASTVORA-KINETIKA PRENOSA MASE ....................... 123
Péter SIPOS, Zsófia SZIGETI, Mária BORBÉLY
EFFECTS OF SALT FORMS AND CONCENTRATIONS ON THE
ALVEOGRAPH PARAMETERS OF WINTER WHEAT /
UTICAJ OBLIKA SOLI I KONCENTRACIJE NA REOLOŠKE OSOBINE OZIME PŠENICE................................................... 126
Zsuzsanna FÜSTÖS, Melanie KOVÁCS
STUDY OF GARLIC ( Allium sativum L.) GROWING TECHNOLOGY
AND VARIETY TYPESUSED IN SERBIA AND IN HUNGARY /
STUDIJA TEHNOLOGIJE PROIZVODNJE RAZLIČITIH VARIJETETA
BELOG LUKA U SRBIJI I MAĐARSKOJ...................................................................................................................................... 129
Dragan MATIĆ, Ilija KAMENKO, Perica NIKOLIĆ, Vladimir BUGARSKI
OPTIMAL CONTROL OF FRUIT AND VEGETABLES DRYING PROCESS /
OPTIMALNO UPRAVLJANJE PROCESOM SUŠENJA VOĆA I POVRĆA................................................................................ 134
Milica NIĆETIN, Lato PEZO , Biljana LONČAR, Vladimir FILIPOVIĆ,
Tatjana KULJANIN, Violeta KNEŽEVIĆ, Danijela ŠUPUT
MASS TRANSFER KINETICS AND EFFICIENCY OF OSMOTIC DEHYDRATION OF CELERY LEAVES /
KINETIKA PRENOSA MASE I EFIKASNOST OSMOTSKE DEHIDRATACIJE LISTA CELERA........................................... 137
LIST OF THE PERMANENT REVIEWERS / LISTA STALNIH RECENZENATA .................................................................... 140
INFORMACIJE ........................................................................................................................................................................ D1 – D2
POSLOVNO STRUČNI DODATAK .................................................................................................................................... D3 – D10
Guide for authors and list of permanent reviewers is on the internet address http://www.ptep.org.rs, as well as in the first issue (No 1)
of each respective year.
Uputstvo za pisanje radova i lista stalnih recenzenata nalazi se na internet adresi http://www.ptep.org.rs/casopis.html, kao i u svakom
prvom broju (No 1) časopisa odgovarajuće godine.
Biblid: 1821-4487 (2014) 18; 3; p 95-99
UDK:669.054
Review Paper
Pregledni rad
PLASMA APPLICATION FOR BIOMATERIALS PROCESSING
PRIMENA PLAZME PRI DORADI BIOMATERIJALA
Ljiljana BABIĆ
University of Novi Sad, Faculty of Agriculture, Trg Dositeja Obradovića 8,
Novi Sad, Republic of Serbia
e-mail: [email protected]
ABSTRACT
An objective of this paper is to offer some basic information about quite new state of matter, to the experts involve in food chain,
because they do not have such equipments in every day life. The fundamental data about plasma as the forth state of the matter are
presented, as well as some physical properties. Some technical solutions of plasma industrial applications for drinking water purification, odour and dust abatement system are described, which are produced by domestic scientific community or foreigner company.
The applying of plasma energy in the food processing is still on experimental level in the laboratories. The results of several authors
study about fruits, vegetables and chicken meat surface area decontamination prior to packaging by the help of cold plasma energy
are presented. Their conclusions are very optimistic, the compact new design should be expecting in close future. The biomaterial
dryers supported by cold or non cold plasma are still in the hand of scientific institutions, some experimental structures are running
in the laboratories, although a lot of hard work about heat and mass exchanges during this process should be done.
Key words: plasma, gases and water purification, biomaterial plasma dryers.
REZIME
Cilj ovog rada je da se inženjerima koji se nalaze u lancu proizvodnje hrane približi jedna za njih nova oblast stanja materije sa
kojom se ne susreću u industrijskim postrojenjima. Predstavljeni su osnovni pojmovi o plazmi, kao četvrtom stanju materije, tako što
su naznačene neke osobine. Posebna pažnja je posvećena postojećim tehničko tehnološkim rešenjima primene plazme kod prečišćavanja pitke i zamućene vode, kao i prečišćavanje produkata sagorevanja i zagađenog vazduha, i to kako stranih kompanija tako
i domaćih rešenja. Primena takozvane hladne plazme pri različitim tretmanima biomaterija, gde su temperatura i pritisak
jonizovanih gasova blizu ambijentale je novijeg datuma. Tako na primer Misra i sadarnici (2013) obaveštavaju o rezultatima
delovanja hladne plazme na površinu jagoda radi eliminisanja mikroflore (aerobne mezofilne bakterije, kvasvi, gljivice). Plazmu su
generisali električnom energijom napona od 60 kV preko dve elektrode u unutrašnjosti hermetički zatvorenog pakovanja voća u trajanju od 5 minuta. Konstatuju da merenjima disanja upakovanog voća nakon 24 časa od tretmana nije bilo značajnog povišenja produkta disanja (vodena para i CO2), i da nije došlo do značajnije promene čvrstoće plodova. Druga grupa autora (Wang R. X, et al.,
2012) je uradila slična istraživanja, ali sa tankim čipsovima napravljenim od sveže mrkve i krastavca. Pripremljene uzorke su inficirali bakterijom Salmonella. Tretman plazmom je trajao 2 minuta i to direktno na površine pri čemu je inaktivirano blizu 90% Salmonelle na uzorke mrkve i oko 80% na uzorku krastavca. Konstatuju da nije došlo do značajnih promena vlažnosti uzoraka, boje i
sadržaja vitamina C tokom tretmana, te na osnovu ovih rezultata preporučuju primenu hladne plazme za dekontaminaciju svežeg
voća i povrća u odgovarajuće. Kada je u pitanju sušenje biomaterijala plazma tehnologijom, generalno se može reći da je ona primenljiva za sitne čestice koje se ne slepljuju. Plazma se u ovom slučaju stvara pomoću spoljnog elektromegnetnog ili električnog
polja, konfiguracijom elektroda realizuje se plamen plazme. Prve informacije o primeni energije plazme (Kudra, Mujumadar, 2002)
za sušenje datiraju iz 1963. godine, a već osamdesetih godina prošlog veka se obavlja sušenje na laboratorijskom nivou mešavine
čiste vode i sodijum nitrata (NaNO3) plamenom plazme u sprej sušari. Druga moguća primena energije plazme u procesu sušenja je
upotreba pregrejane vodene pare, gde plamen plazme može da obezbedi početne temperature plazme od 550 do 1400 K, a konstrukcija sušare je takva da se materijal suši u oblasti pneumatskog transporta.
Ključne reči: plazma, prečišćavanje gasova i vode, plazma sušara za biomaterijale.
INTRODUCTION
The term plasma was introduced by Irving Langmuir (Piel,
2010) in the first half of 20 century to describe the chargeneutral part of a gas discharge. David A. Frank-Kamenezki was
the first one why identified plasma as the fourth state of matter
(Piel, 2010). This view alludes to the four elements of preSocratic Greek philosophy, like Earth (solid), Water (liquid), Air
(gaseous) and Fire. On the other hand, the ideas on a fourth state
of matter go back to Michael Faraday (1791-1867), who, in
1809, speculated about a radiant state of matter he associated
with the luminous phenomena produced by electric currents
flowing in gases. The results of plasma study by researchers
showed in the last 20 years that plasma systems can attain gaseous, liquid and even solid phases.
Journal on Processing and Energy in Agriculture 18 (2014) 3
The identification of plasma as a new state of matter can be
justified because the splitting at high temperature of neutral atoms into electrons (negative electrified) and atom nucleus (positive electrified), by the help of large amount of introducing energy. This process is associated with a new energy barrier, the
ionization energy.
The matter in plasma state is an electrically conductive medium, which possesses a number of new properties that distinguish it from neutral gases and liquids. Most of the visible matter in space is in the plasma state. Electro conductivity is physical property of plasma, which causes magnetic and sparkling
properties, which is the only one detected by human eyes. Generally speaking, living on the planet Earth which provides cold
condition (compare to stars) the human experience with matter is
connected with three states as natural ones.
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Babić, Ljiljana / Plasma Application for Biomaterials Processing
Plasma science is an old discipline of physics, the roots of
plasma physics are related to the history of electricity. The significant number of scientific and innovators done tests in order
to be more familiar with the processes in nature, especially with
the properties of light. Pieter van Musschenbroek (1692-1686)
invented the Leyden jar, a high-voltage capacitor. Leyden jar
produced a spark in air, it sounded like a gunshot, from which
the terminology gas discharge arose. When high-current electric
batteries became available, the electric arc was discovered in the
year 1803, by Vasily V. Petrov and independently by Humphrey
Davy (Piel, 2010). Michael Faraday discovered electric glow
discharges in rarefied gases and made many years investigations.
Even a great Isaak Newton was involved in such kind of study.
Nicola Tesla (1856-1943), in the year 1891, started with electric
discharges study driven by high frequency electric fields. In this
pre-historic era of plasma physics, Tesla was found that gas discharges involved the motion of electrons and positive ions,
which represents the electric current flowing in a gas.
An electron which circled on certain path around the core of
atom was discovered and named by Joseph John Tomson in the
year 1897, six years after Tesla done his tests with electricity.
The discovery of collective phenomena in gas discharges, which
define the modern concept of plasma and their proper explanation by mathematical models, was left to the 20th century. The
systematic research of the plasma state and the formulation of
general laws were presented in the work of Irving Langmuir and
his co-workers, during the 1920. Today’s plasma physics rests
on radio science, which deals with the propagation of electromagnetic waves in the ionosphere. Since the mid of 1950s, research on controlled nuclear fusion established the field of hotplasma physics. Scientific questions like confinement of hot
plasmas by magnetic fields and plasma instabilities became important.
An objective of this paper is to offer some basics information
about the fourth state of matter to food engineers and to present
the possibility of plasma application in variety branches of food
processing. The production of food from field to the table needs
a certain amount of energy; therefore the plasma energy will be
probably introduced in these human activities.
of plasma. An energy of plasma is huge magnetic structure,
wrapped in corona. When coronal mass ejections it release abot
1.6 x 1012 kilograms of plasma moving at a speed between 2002700 km/s. The space between Sun and our is filled with the
plasma of the solar wind. The solar wind which is the charge of
particles, may be headed toward the Earth when the plasma hits
the planet magnetosphere and creates magnetic storms.planet
.
Fig. 1. The corona of Sun (www.svemir.wordpress.com)
The solar wind (Fig. 2) is consist of protons, electrons and
helium ions, the temperature of protons in plasma is 1.86 105 K
and electrons 0.84 105 K. The storms may lead to disruptions in
power line grids by large induced currents, can damage communication satellites and have a hazard impact for astronauts. The
interaction between solar wind and Earth magnetic field is can
be very spectacular in the nature.
Some of the particles in plasma may flow along the magnetic
field lines of the Earth in the upper atmosphere by polar altitudes, which couses the curtain like Aurora borealis or Northern
Lights.
The plasma origin on the planet earth
The plasma origins on our planet the Earth
from nearest star Sun. Sun is active star. This star
produces enough amount of thermal radiation to
surveves the life at the planet. Sun is stady-state
fusion reactor that converts protons to havier elements (Piel, 2010) and produce enegy. This
amount of energy supports the stability of Sun’s
core, where the temperature is about 15 x 109 K.
In the same time this energy provides very high
pressure in the vary centre of star, that holds the
matter in one piece and prevents the collapse of
the star. The heat energy transports from the star
core towards the foreign area by conduction
(www-spof.gsfc.nasa.gov), therefore the temperature of the Sun’s surface is 5780 K.
This energy is spreaded in cosmos space by
convection and radiation. The radiation energy
(explosive emission) is registered by satellites
(Fig. 1) in the case when Moon completely covers
the star, and is named corona (www.
svemir.wordpress.com), this is indeed the energy
96
Fig. 2. An effect of solar wind onto magnetic field of Earth
(www.solar+winds&source.com)
Journal on Processing and Energy in Agriculture 18 (2014) 3
Babić, Ljiljana / Plasma Application for Biomaterials Processing
Man-made plasma applications
The creation of plasma under the conditions made by man is
so called cold plasma, compare to hot plasma produced by Sun
as the results of fusion process. Cold plasma is made under
much lower values of the temperature and pressure of gases.
This plasma is driven by electrical current, the final products are
fluorescent tubes, photographic flash tubes, plasma TV’s, high
power arc lamps for data projectors or street illumination and
many other industrial applications like etching of silicon wafers
or silicon deposition on substrates for manufacturing solar cells
and computer displays. Lighting is one of the traditional domains for plasma applications. Electric arcs in high-pressure
lamps are used for street lights and low-pressure discharges in
fluorescent tubes for office and domestic lighting. The enormous
energy saving was achieved by plasma-based lighting steam because of efficient use of radiation within the range of spectral
sensitivity of the human eye. The application of plasma is in
cleaning, etching, activating and coating some surfaces whose
are optimal basis for gluing, binding or painting, thus give an
added value to product surface.
Cold plasma has important and quite innovative application
in the industry for remove the pollutants from the air and water.
The technology follows the same principles as those of self
cleaning atmosphere, but on much faster rate. In the plasma zone
molecules are bombarded by electrons creating ions and charged
material. Those primary created ions may generate secondary
radicals, of which oxygen atom radicals are the most important.
Cold plasma module (Fig. 3) remove odor and particles in very
large scale of human activities, like in the industry of fish processing, in edible oil production, production of pet food, in processing of tobacco for cigarettes, in the coal drying for huge energetic system support, ect.
Fig. 3. Cold plasma module for odor and dust abatement
(www.app.no)
The main component of odor and dust abatement system is
cold plasma modul, where an ozone is produced by the help of
electrical current. Electrons collide with the gas molecules and
create chemically active species known as radicals, like atomic
oxygen (O3) and hydroxyls (OH). The radicals react with pollutant molecules in the gas steam, breaking them down into less
hazardous or more easily handed components. Radicals are
slicked to the inner walls of reaction chamber (Fig. 4).
Fig. 4. Reaction chamber acts like electrostatic precipitator
(www.app.no)
Journal on Processing and Energy in Agriculture 18 (2014) 3
Test had shown that the system is very effective in removing
fine dust and submicron particles down to 2.5 μm and below.
The company Applied Plasma Physics from Norway have been
produced 37 of such systems and installed them all around the
world.
Similar technological and technical solution may be provided
by Center for Science and Technology Development, Faculty of
Physics, University of Belgrade (www.center.bg.ac.rs). The difference is in the material which is used for reaction chamber assembling, those are the pipes made of glass (Fig. 5). An elimination of pollutants like SOx, NOx, soot and organic volatiles in
plasma module is important action of environmental protection
and human well being conditions.
Fig. 5. Cylinder made of glass in reaction chamber
(www.center.bg.ac.rs)
The plasma modules are built in thermal power plant „Nikola
Tesla“ in Obrenovac for denitrification and containing sulphur
elimination from the out going gases, as well as for purification
of exit gases from coal dryer in Vreoci.
Center for Science and Technology Development, Faculty of
Physics, University of Belgrade has designed plasma water
ozonisator system operates in the air at an atmospheric pressure
(Fig. 6). One of the dielectric layers in reactor is flowing water.
Ozone and ozonized water are generated in the same volume of
the discharge. The ozone production and its dissolution in the
water simultaneously occurs leading to increases of the reactor
efficiency. Water flows up through a vertical hollow cylindrical
electrode and flows down making thin dielectric film over the
electrode (Fig. 7). Filamentary discharge is generated in air
within 4 mm gap between the dielectric and the water layer. The
inner electrode is 400 mm length and 20 mm in diameter. A
measured power, under such condition, using a method of Lissajous figures is found to be from 7 to 9 W for the flow rates in the
range of 200 to 500 ml/min.
Fig. 6. Plasma water ozonizator reactor at
atmospheric pressure (www.center.bg.ac.rs)
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Babić, Ljiljana / Plasma Application for Biomaterials Processing
Fig. 7. Water ozonisation by the system of electrodes
(www.center.bg.ac.rs)
1-tank with water for purification, E1,
E2- electrode, 2. deposit tank,
3. purified water flow to the upper tank or to consumption
The obtained ozone concentrations correspond to the values
typically suggested for the treatment of potable and wastewater.
The efficiency can be further increased by addition of small
amount of the oxygen in the reactor.
Interesting application of atmospheric or low pressure
plasma is in some pretreatment procedure of different packaging
materials in order to increase surface tension and to achieve
radical positions of better lacquer or sticking adhesion
(www.enerconind.com). The treatment of surface by low pressure plasma removes organic and non organic contaminants.
Plasma treatment is effective on polymers, elastomers, glass and
metals. Plasma treatment heads can be mounted in a fixed position over a conveyor or indexing system. They may also be integrated with robotics for precise treatment patterns. Plasma treating is used extensively prior to printing, painting, decorating,
bonding and assembly in the automotive, medical, converting,
solar, construction, manufacturing and plastics industries.
Canadian Electrical Association was interesting to make a
review of plasma technology and assess the potential for application of this technology in Canada (Drouet, 1984). A team of experts in the various aspects of this technology was assembled
and each team member was asked to contribute to this report on
the applications of plasma pertinent to his or her particular field
of expertise. The following areas were examined in detail: iron,
steel and strategic-metals production; surface treatment by
spraying; welding and cutting; chemical processing; drying; and
low-temperature treatment. A large market for the penetration of
electricity has been identified. To build up confidence in the
technology, support should be provided for selected R and D
projects, plasma torch demonstrations at full power, and largescale plasma process testing.
Biomaterials processing treatments
supported by plasma
Cold plasma is a novel non thermal food processing technology that uses energetic, reactive gases to inactivate contaminating microbes on meats, poultry, fruits, and vegetables. This
flexible sanitizing method uses electricity and a carrier gas, such
as air, oxygen, nitrogen, or helium; antimicrobial chemical
agents are not required. The primary modes of action are due to
UV light and reactive chemical products of the cold plasma ionization process. A wide array of cold plasma systems that operate
98
at atmospheric pressures or in low pressure treatment chambers
are under development. According to Niemira (2012) the reductions of greater than 5 log can be obtained for pathogens such as
Salmonella, Escherichia coli O157:H7, Listeria monocytogenes,
and Staphylococcus aureus. Effective treatment times can range
from 120 s to as little as 3 s, depending on the food treated and
the processing conditions. According to authors, key limitations
for cold plasma are the relatively early state of technology development, the variety and complexity of the necessary equipment, and the largely unexplored impacts of cold plasma treatment on the sensory and nutritional qualities of treated foods.
Also, the antimicrobial modes of action for various cold plasma
systems vary depending on the type of cold plasma generated.
Optimization and scale up to commercial treatment levels require a more complete understanding of these chemical processes.
The ability to generate low temperature plasma at atmospheric pressure offers new opportunities to decontaminate biological materials, including fresh foods. In this study of Misra et
al. (2014) strawberries were treated with atmospheric cold
plasma (ACP), generated with a 60 kV dielectric barrier discharge (DBD) pulsed at 50 Hz, across a 40 mm electrode gap,
generated inside a sealed package containing ambient air (42 %
relative humidity). The current–voltage characteristics revealed
that the plasma operated in the filamentary regime. The background micro flora (aerobic mesophillic bacteria, yeast and
mould) of strawberries treated for 5 min was reduced by 2 log
within 24 h of post-ACP treatment. The respiration rate of ACP
treated produce, measured by the closed system approach,
showed no significant increase. The effect of ACP on strawberry
colour and firmness was insignificant.
A direct-current, atmospheric-pressure air cold plasma micro
jet (PMJ) was applied to disinfect Salmonella directly deposited
on fresh fruit and vegetable slices (Wang et al, 2012). Effective
inactivation was achieved on sliced fruit and vegetables after 1 s
plasma treatment. The physiochemical properties of the slices,
such as water content, color parameters, and nutritional content
were monitored before and after plasma treatment. It was found
that the physiochemical properties changes caused by the plasma
were within an acceptable range. Reactive oxygen species,
which are believed to be the major bactericidal agents in the
plasma, were detected by electron spin resonance spectroscopy
and optical emission spectroscopy.
Nonthermal plasma has been shown to be effective in reducing pathogens on the surface of different kind of meat. The research presented by Dirks et al (2012) were investigated the effectiveness of nonthermal dielectric barrier discharge plasma on
Salmonella enterica and Campylobacter jejuni inoculated onto
the surface of boneless skinless chicken breast and chicken thigh
with skin. The samples were exposed to plasma for a range of
time from 0 to 180 s. Inoculum levels of 102, 103, and 104 CFU
of S. enterica on chicken breast and chicken skin resulted in
maximum reduction levels of 1.85, 2.61, and 2.54 log, respectively, on chicken breast and 1.25, 1.08, and 1.31 log, respectively, on chicken skin following by 3 min of plasma exposure.
Plasma technologies are suited to handle small particles
which are in the shape of pellets, for different drying processes.
Therefore, the fluidized bed, spouted bed, or spray dryers will be
appropriate technologies. The creation of plasma is by external
electromagnetic or electrical fields. Electrodeless device can be
used for cold plasma creation in quartz tube by high frequency
electromagnetic energy. The first information about drying process support by plasma energy (Kudra and Mujumadar, 2002) is
from the year 1963, but in the year 1986 the laboratory test of
pure water and sodium nitrate solution was done in spray dryer
Journal on Processing and Energy in Agriculture 18 (2014) 3
Babić, Ljiljana / Plasma Application for Biomaterials Processing
(Fig. 9). The high entalpy of superheated plasma was rapidly
cooled by the water vapour, therefore the finish of drying process was performed in a gases mixture of 94 % vapour and 6 % of
nitrogen. The amount of water vapour from drying process
makes the environmental condition in the chamber similar to the
airless drying technique. This condition results in reduction of
dryer size and in large decreases in energy consumption.
The important result of this study is that the superheated water vapour, produced by plasma energy, can be a heat source for
drying.
CONCLUSION
Instead of conclusion it is appropriate to cite the opinion of
dr Alexander Peil professor of Christian-Albrechts-Universitat,
Kiel in Germany:
“Our technical age is unthinkable without plasma. Plasma
arc switches are used in the distribution of electric energy; highpressure lamps illuminate our streets and serve as light sources
in modern data projectors; fluorescent tubes light our offices and
homes; computer chips are etched with plasma technologies;
plasma-assisted deposition processes result in flat computer
screens and large-area solar cells. The future energy supply may
benefit from electricity produced by controlled nuclear fusion.
These different phenomena can be described in a unified way by
fundamental concepts”.
It is important to emphasize that the people have only indirect experience about plasma, it cannot be touch, the plasma
cannot be hear, there is no information about the taste or smell of
plasma. Only visual experience exists, that is shining. That is the
reason why scientists are looking for indirect approval about
plasma, searching for plasma physical properties like density,
temperature or the way of movement plasma in the space.
ACKNOWLEDGEMENT: This paper has been supported by
Ministry of education, science and technological development,
Republic of Serbia, grant of project No TR31058, 2011-2015.
REFERENCES
Fig. 8. Plasma spray drying sistem
The initial temperature of super heated water vapour by the
action of plasma is from 500 to 650 K, this value drop to 370 K
in the lower section of dryer (Fig. 9), if the material feeding is
high enough (Kudra and Mujumadar, 2002). The construction of
this dryer is flash dryer, that means the material is drying in the
range of pneumatic value velocities.
The amount of energy in this dryer is 6000 kW for drying 20
t materials per day. This system is suitable for operation with
cold plasma and under the condition of pressure reduction in the
system.
Fig. 9. Exsperimental plasma phneumatic dryer
(Kudra, Mujumadar 2002)
Journal on Processing and Energy in Agriculture 18 (2014) 3
Dirks, B. P., Dobrynin D, Mukhn, Y., Quinlan J. J. (2012).
Treatment of row poultry with nonthermal dielectric barrier
plasma to reduce Campylobacter jejuni and Salmonella
enterica. Journal of Food Protection, 7, (1), 22-28.
Drouet, M. G. (1984). Plasma technology: Review of the stateof-art and its potential in Canada. Canadian Electrical
Association. R. No 126U322.
Kudra, T., Mujumadar, A. S. (2002). Advanced drying
technologies. Marsel Dekker, Inc, New York, 459.
Misra, N. N., Patil, S., Moiseev, T., Bourke, P., Mosnier, J. P.,
Keener K. M., Cullen P. J. (2014). In-package atmospheric
pressure cold plasma treatment of strawberries. Journal of Food
Engineering, 125, 131-138.
Niemira, B. (2012). Cold Plasma Decontamination of Foods.
Annual Review of Food Science and Technology, 3, 125-142.
Piel, A. (2010). Plasma physics – An introduction to laboratory,
space and fusion plasmas. Springer-Verlag Berlin Heidelberg,
344.
Wang, R. X., Nain, W. F., Wu, H, Y., Feng, H. Q., Zhang J,
Zhu, W. D. (2012). Atmospheric-pressure cold plasma
treatment of contaminated fresh fruit and vegetable slices:
inactivation and physiochemical properties evaluation. The
European Physical Journal D. 66-276.
www.center.bg.ac.rs
www.app.no
www-spof.gsfc.nasa.gov
www.svemir.wordpress.com
www.enerconind.com
www.solar+winds&source.com
Received: 31.01.2014.
Accepted: 14.03.2014.
99
Biblid: 1821-4487 (2014) 18; 3; p 100-102
UDK: 542.934.8:641.12
Original Scientific Paper
Originalni naučni rad
THE GLASS TRANSITION OF OSMOTICALLY
DEHYDRATED PORK MEAT
STAKLASTI PRELAZ OSMOTSKI DEHIDRIRANOG
SVINJSKOG MESA
Sanja OSTOJIĆ*, Darko MICIĆ*, Mirjana PAVLOVIĆ*, Snežana ZLATANOVIĆ*,
Olgica KOVAČEVIĆ*, Branislav R. SIMONOVIĆ*, Ljubinko LEVIĆ**
*
University of Belgrade, Institute of General and Physical Chemistry,
Studentski trg 12, 11000 Belgrade, Serbia
**
University of Novi Sad, Faculty of Technology, Bul. Cara Lazara 1, 21000 Novi Sad, Serbia
e- mail : [email protected]
ABSTRACT
Thermal behavior of and fresh and osmotically dehydrated pork meat in sugar beat molasses pork meat was studied by Differential scanning calorimetry (DSC). Samples of 7–11 mg (moisture content 5-20%) of osmotically dehydrated pork meat in aluminum
pans were cooled from 20°C to −90 °C, equilibrated for 5 min and scanned initially from −90 °C to 150 °C at a rate of 5°C/min. The
glass transition temperature (Tg) was determined from the DSC heat flow curves with TA Advantage software. Since much of the water was bound to the solid matrix, samples with low moisture content only showed up the glass transition. Tg decrease with increasing
moisture content. Tg decreased from −6.0 °C to −10.1 °C when the moisture content increased from 5% to 20%. DSC curves of fresh
pork meat did not showed the glass transition.
Key words: pork meat, osmotic dehydration, glass transition, differential scanning calorimetry.
REZIME
Termalne karakteristike svežeg i osmotski dehidriranog svinjskog mesa u melasi šećerne repe, praćene su metodom diferencijalne
skenirajuće kalorimetrije (DSC). Uzorci osmotski dehidriranog svinjskog mesa, mase od 7–11 mg (sadržaj vlage 5-20%) hlađeni su
od 20°C do −90 °C, uravnoteženi 5 min a zatim grejani od −90 °C do 150 °C brzinom grejanja 5°C/min. Temperatura staklastog
prelaza (Tg) određena je iz dobijene DSC krive pomoću programa TA Advantage. Kod uzoraka s malim procentom vlage, nađen je
staklasti prelaz, pošto je veliki udeo vode vezan za čvrsti matriks. Povećavanjem sadržaja vlage u uzorku (5-20%) snižavaju se temperature staklastog prelaza od −6,8 °C do −10,3 °C. Rezultati DSC analize svežeg mesa pokazali su izostanak staklastog prelaza.
Ključne reči: svinjsko meso, osmotska dehidratacija, staklasti prelaz, diferencijalna skenirajuća kalorimetrija.
INTRODUCTION
The importance of Tg of amorphous food materials for
processing and storage stability has been recognized and emphasized by many researchers and a wide range of potential food
applications of the glass transition phenomenon have been identified (Shia et al., 2009). Water activity (aw) and glass transition
temperature (Tg) provide valuable information on the effects of
water content on water availability in foods and on the physical
state of food solids (Roos, 1995). Water activity, which is defined by the chemical potential of water, measures the availability of water for deteriorative changes or microbial growth. Glass
transition is a second-order phase transition, a property of the
food matrix that occurs over a characteristic glass transition
temperature range (Roos, 2003), and it is a highly important characteristic in understanding many aspects of food stability and
processing. For many decades, the concept of aw has been sufficient to describe the stability of food products. It has been argued that aw is not sufficient to describe the secondary processes
of change-in-state in foodstuffs thus ushering in the concept of
glass transition temperature (Slade and Levine, 1991). Over the
last two decades, much research has been reported on the importance of glass transition for a large variety of food materials and
ingredients. As aw was proved to be inadequate in some cases,
the concept of glass transition was used as a parameter for quantifying water mobility and food stability, which became popular
in the late 1980s (Oliveira et al., 1999). Biological materials are
rigid and brittle below the glass transition temperature. Nevertheless, they are not crystalline with regular structure but retain
the disorder of the liquid or amorphous state (Rahman et al.,
2003). The physical state of foodstuffs is very stable below the
glass transition temperature because compounds involved in de-
100
terioration reactions take many months or even years to diffuse
over molecular distances, and approach each other to react
(Slade and Levine, 1991). Furthermore, water molecules become
kinetically immobilized within the concentrated phase, thus being unable to support or participate in the reactions causing deterioration (Mitchell, 1998). Most scientists concur that the glass
transition temperature under conditions of maximal freeze concentration, Tg, is the technologically significant transition which
has the greatest influence on low-temperature stability
(Goff, 1994). The consequence as far as food products are concerned is that a small change in temperature in the vicinity of the
glass transition temperature will result in pronounced changes in
the sensory properties of texture and other dynamic properties
(Simatos et al., 1995, Delgado and Sun, 2002). Glassy and freezing characteristics of pure substances are more commonly reported than that of real foods, which are complex multicomponent mixtures (Rahman et al., 2003). The glass transition temperatures of freezedried strawberry and cabbage are available
and were measured as a function of water content by Roos
(Roos, 1995) and Paakkonen and Plit (Paakkonen and Plit,
1991), respectively, using differential scanning calorimetry
(DSC). Brake and Fennema, 1999 and Inoue and Ishikawa, 1997
also measured the glass transition of fresh muscle tissue by DSC.
Brake and Fennema, 1999 pointed out on the importance of the
annealing for Tg, determination, and found that apparent Tg, of
mackerel, cod and beef were similar (ca -11 to -13ºC) and substantially higher than most published values (-15 ºC to -77 ºC for
tuna and beef). Inoue and Ishikawa, 1997 found that glass transition of fresh red meat of bigeye tuna (Thunnnas obesus) and its
filtrate occurred between -71ºC and -68 ºC, independent of cooling rate from 1 K/min up to 50 K/min. Also the same authors
showed that the transition at low temperature appeared to occur
in the liquid part and neither dilution nor concentration of the
Journal on Processing and Energy in Agriculture 18 (2014) 3
Ostojić, Sanja et al. / The Glass Transition of Osmotically Dehydrated Pork Meat
filtrate affected the glass transition temperature (Tg) but the solute concentration of the freeze concentrated phase (Cg) was affected.
The objective of the present study was to define thermal behavior of fresh and osmotically dehydrated pork meat considering glass transition.
MATERIAL AND METHOD
Preparation of osmoticaly dehydrated pork meat (Musculus
brachii) in sugar beat molasses has been described elsewhere
(Šuput et al., 2013, Pezo et al., 2013 ). A differential scanning
calorimeter (DSC, Q1000, TA Instruments, New Castle, DE)
equipped with Refrigerated Cooling System (RCS, TA Instruments, New Castle, DE), was used to perform DSC experiments.
The calorimeter was calibrated according to the instruction provided by TA instruments user manual by checking temperature
and enthalpy of fusion of indium as standard. Osmoticaly dehydrated pork meat samples (7–11 mg) with different water content, were placed in aluminum pans and subjected to cooling and
heating, in the temperature range from -90 ºC to 150 ºC, with
controled heating rate Hr=5 ºC/min, under the N2 purge flow of
50 ml/min.
First, samples were cooled to −90 ºC and equilibrated for 5
min and then scanned from −90 ºC to 150 ºC at a heating rate of
5ºC/min. The wather content was estimated by
Thermoogravimetric analysis (TGA). TGA measurements were
performed on TGA Q 500, (TA Instruments, New Castle, DE)
under N2 purge flow of 60 ml/min and 40 ml/min, in sample and
balance, respectively. All TGA scans were performed in temperature range 25 ºC-900 ºC, and heating rate Hr= 5 ºC/min.
Each thermogram was analyzed by TA Advantage Universal
analysis 2000 software to obtain the glass transition parameters
(onset, Tonset; midpoint, Tg; final ,Tend) for the onset, mid and end
of transition, and also to obtain the percentage of mass loss from
TGA curves.
Three replicates were used for selected samples (water content). For the materials showing wide peak of ice melting on the
DSC thermogram, the point of maximum slope corresponds well
with the initial freezing point estimated from cooling curve method (Sablani et al., 2007). The enthalpy of ice melting was estimated from the area of the melting endotherm. The average
values and standard deviation of three replicates were obtained
for selected data point to identify the experimental variability.
The water activity (aw) has been determined by thermoanalytical techniques as previously described by de Silva et al.
2008).
RESULTS AND DISCUSSION
Thermal behavior of pork meat samples are shown in Figures 1.a), b) and 2. For fresh pork meat (moisture content 75%),
the heat flow curve obtained from DSC showed three characteristic transitions (Fig.1. a) with peak maximums at about -0.3
ºC, 69 ºC and 93 ºC which represents ice melting, water evaporation and meat protein denaturation with total enthalpy of 970 J/g,
respectively. First transition, at -0.3°C, corresponds to the ice
melting, second transition, which occurs at 69ºC, was assigned
to collagen (Stabursvik and Martens, 1982) and the third transition has been assigned to actin denaturation (Stabursvik and
Martens, 1980). In Fig. 1. b) DSC curve of osmotically dehydrated pork meat (moisture content 38.1%) is presented. For osmotically dehydrated pork meat the heat flow curve obtained
from DSC showed two characteristic endothermal transitions
(Fig.1. b). The first one, with peak maximum at -16 ºC
represents ice melting and second one, corresponds to the
process of protein denturation which is accompanied with water
evaporation, and presented as one broad endothermal peak with
temperature maximum Tm=63 ºC and total enthalpy (ΔH) of 529
Journal on Processing and Energy in Agriculture 18 (2014) 3
J/g. Decreased enthalpy and temperature maximum of transition
which represents meat protein denaturation of osmoticaly dehydrated pork meat (second transition) compared to for fresh pork
meat (second transition) suggest that destabilization of meat proteins and conformational changes were induced by the process of
osmotic dehydration. These changes of material thermal behavior were consequence of water loss and interaction with molasses components. This is a typical DSC thermogram of sample
having freezeable water without annealing (Fig. 1. b), in accordance with literature (Shia et al., 2009). It showed ice melting
point (-31.4 ºC), with total enthalpy of trasition ΔH=38.6 J/g .
a)
b)
Fig. 1. Typical DSC curve of a) fresh pork meat and b) osmotically dehydrated pork meat
Further loss of water leads to new changes in the material
and the appearance of characteristic thermal behavior for samples having unfreezible water (Shia et al., 2009, Sablani et al.,
2007, Delgado and Sun, 2002, Rahman et al., 2003). Since
much of the water was bound to the solid matrix, samples of dehydrated pork meat with low moisture content (below 20%) only
showed up the glass transition. As expected Tg decreased with
increasing moisture content, as shown in Table 1.
Table 1. Water content, glass transition temperature,
freezing point and water activity of osmoticaly dehydratated
pork meat with freezable and unfreezible water
Moisture (%) Tonset (ºC) Tg (ºC) Tend (ºC) Ice melting (ºC)
38.10
-37.41.0
35.02
-33.40.9
26.28
-33.70.8
20.70
-31.61.1
5.90
-20.23.0 -10.31.1 -2.622.5
3.77
-17.23.1 -6.81.0 -1.812.7
aw
0.745
0.732
0.724
0.720
<0.7*
<0.7*
*Cannot be determined by thermoanalytical techniques in
samples having unfreezible water.
Tg decreased from −6.8 ºC to −10.3 ºC when the moisture
content increased from 4 to 20 % (Table 1).
For pork meat with water content from 20% to 4% the heat
flow curves obtained from DSC showed up the characteristic
glass transition (Fig. 2).
Figure 2. Typical DSC curve of osmotically dehydrated pork
meat with low moisture content (<20% )
101
Ostojić, Sanja et al. / The Glass Transition of Osmotically Dehydrated Pork Meat
A decrease in heat flow caused by a glass phase transition
was observed in the thermogram in temperature region from -5
ºC to – 25 ºC, and disappearance of endothermic peaks between
-30 ºC to 150 ºC, usual for samples having freezable water, occurred (Fig. 1.b and Fig. 2). The glass phase transition was found
consistently in samples of different aw and water content (Shia et
al., 2009, Kawai et al., 2005). It was reported that two kinds of
glass transitions have been observed with protein–water systems.
One is known to be at low temperatures (around −113 ºC to −73
ºC) which are associated with freezing of motions of water molecules (Sablani et al., 2007). However, the transition observed
in this work was at a relatively higher temperature which could
be due to the initiation of mobility in protein molecules what is
agreeable to literature (Sablani et al., 2007, Shia et al., 2009). It
can be assumed that initiation of protein molecules mobility
could be induced not only by water loss but also with protein
interaction to molasses components. On the other hand, results
obtained in this work are in agreement with results obtained by
Brake and Fennema 1999, who found that apparent Tg of mackerel, cod and beef were similar (-11 ºC to -13 ºC) and substantially higher than most published values (-15 ºC to -77 ºC for
tuna and beef), but in accordance with expectations for substances of high molecular weight. Samples with higher water
content (from 26 to 38 %) did not have glass transition in studied
temperature range. In the Table 1 are also given the ice melting
point temperatures as a function of moisture content. The results
showed that ice melting increased with increasing of solid content.
CONCLUSION
The samples of osmotically dehydrated pork meat with different moisture percentage and aw value behaved differently
during DSC scanning. Since much of the water was linked to the
solid matrix, samples with low moisture content (under 20%)
only showed up the glass transition. As expected Tg decreased
with increasing moisture content: Tg decreased from −6.8 ºC to
−10.3ºC when the moisture content increased from 4 to 20%.
DSC curves of fresh pork meat did not showed the glass transition under scanning conditions applied in this work.
Glass transition temperatures Tg observed in this work was at
a relatively higher temperature but still agreeable to literature
(Sablani et al., 2007, Shia et al., 2009, Brake and Fennema,
1999). It can be proposed that initiation of protein molecules
mobility could be induced not only by water loss but also with
protein interaction to molasses components. Further studious investigations are necessary. Obtained data of sample thermal behavior can be useful in the construction of a state diagram for
osmotically dehydrated pork meat.
ACKNOWLEDGMENT:This work was supported by the
Ministry of Education, Science and Technological Development
of the Republic of Serbia, under the Projects No TR-31055 and
TR-31093.
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glass transition temperature for chicken meat. Journal of Food
Engineering, 55, 1–8.
Goff, H. D. (1994). Measuring and interpreting the glass
transition in frozen foods and model systems. Food Research
International, 27, 187–189.
Inoue, C., Ishikawa, M. (1997). Glass transition of tuna flesh at
low temperature and effects of salt and moisture. Journal of
Food Science, 62, 496–499.
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albuminThermochim. Acta, 431, 4–8.
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Hill, D. A. Ledward, & J. R. Mitchell (Eds.), Functional
properties offood macromolecules (pp. 50–76). Gaithersburg:
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Oliveira, J. C., Pereira, P. M., Frias, J. M., Cruz, I. B., MacInnes,
W. M. (1999). Application of the concepts of biomaterials
science to the quality optimization of frozen foods. In F. A. R.
Oliveira, & J. C. Oliveira (Eds.), Processing foods quality
optimization and process assessment (pp. 107–130). USA:
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Paakkonen, K., Plit, L. (1991). Equilibrium water content and
the state of water in dehydrated white cabbage. Journal of Food
Science, 56(6), 1597–1599.
Pezo, L., Ćurčić, Biljana, Filipović, V., Nićetin, Milica,
Knežević, Violeta, Šuput, Danijela (2013). Primena difuznog i
nekih empirijskih modela za predviđanje gubitka vode i
priraštaja suve materije tokom osmotskog tretmana svinjskog
mesa, Journal on Processing and Energy in Agriculture, 17, (2)
68-72.
Rahman, M. S, Kasapis, S, Guizani, N, Al-Amri, O.S. (2003).
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Roos, Y. H. (1987). Effect of moisture on the thermal behavior
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How do they complement and how do they differ. In G. V.
Barbosa-Canovas, & J. Welti-Chanes (Eds.), Food preservation
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154). USA: Technomic Publishing
Roos, Y. H. (2003). Thermal Analysis, State Transitions And
Food Quality, Journal of Thermal Analysis and Calorimetry,
71, 197–203.
Simatos, D., Blond, G., & Perez, J. (1995). Basic physical
aspects of glass transition. In G. V. Barbosa-Canovas, & J.
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da Silva Vilma Mota, da Silva Luciana Almei,. de Andrade J. B,
da Cunha Veloso, Santos Gislaine Vieira (2008).
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and fish bythermoanalytical techniques, Quim. Nova, 31 (4),
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Chang-Hu, (2009). Glass transition and state diagram for
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Received: 28. 02. 2014.
Accepted: 28. 03. 2014.
Journal on Processing and Energy in Agriculture 18 (2014) 3
Biblid: 1821-4487 (2014) 18; 3; p 103-106
UDK: 621.86:662.767.2
Original Scientific Paper
Originalni naučni rad
DETERMINATION OF SOME PHYSICAL PROPERTIES OF
BIOMASS FOR THE PURPOSE OF PNEUMATIC TRANSPORT
ODREĐIVANJE NEKIH FIZIČKIH SVOJSTAVA BIOMASE
ZA POTREBE PNEUMATSKOG TRANSPORTA
Maša BUKUROV*, Siniša BIKIĆ*, Bojan MARKOVIĆ*, Ivan PAVKOV**, Milivoj RADOJČIN**
*University of Novi Sad, Faculty of Technical Sciences, 21000 Novi Sad, Trg Dositeja Obradovića 6, Serbia
** University of Novi Sad, Faculty of Agriculture, 21000 Novi Sad, Trg Dositeja Obradovića 8, Serbia
e-mail:[email protected]
ABSTRACT
The scope of the research presented in this paper is agricultural biomass which becomes more and more interesting as a fuel, especially for the production of heat. The easiest way to manipulate agricultural residues in the processes, either for production of pellets or in the system for boiler feeding, is to apply pneumatic transport. For the purpose of pneumatic transport, biomass should be
grinded into smaller particles. In order to design pneumatic transport it is necessary to know some of the physical characteristics of
these particles. There is not enough data in the literature on properties of agricultural biomass such as: bulk density, particle distribution, density, porosity and humidity. The aim of this paper is to show the application of methods for obtaining these parameters.
The methods are applied to a sample of raw sunflower husks. The principal methods of determining the physical properties of biomass are experimental. A sample of raw sunflower husks is obtained from one Vojvodinian agricultural household and was prepared
for testing.
Key words: density, bulk density, porosity, humidity, agricultural waste, biomass, pneumatic transport of biomass.
REZIME
Predmet istraživanja u ovom radu je poljoprivredna biomasa koja postaje sve interesantniji vid goriva, pogotovo za proizvodnju
toplote. Najjednostavnija manipulacija poljoprivrednih ostataka, bilo da je u pitanju proizvodnja peleta ili dopremanje poljoprivredne biomase u dozatore ispred kotla, obavlja se pneumatskim transportom. Za potrebe pneumatskog transporta potrebno je usitniti biomasu kako bi se oblik dobijenih čestica približio sfernom. Pri projektovanju pneumatskog transporta potrebni su podaci o
fizičkim karakteristikama biomase kao što su: gustina, raspodela čestica, nasipna gustina, poroznost i vlažnost. Ovi podaci su retko
dostupni u literaturi. Cilj rada je prikaz primene metoda dobijanja navedenih parametara. Metode su primenjene na uzorku sirove
suncokretove ljuske. Primenjene metode određivanja fizičkih karakteristika biomase su eksperimentalne. Uzorak sirove suncokretove
ljuske dobijen iz jednog vojvođanskog poljoprivrednog domaćinstva pripremljen je za potrebe ispitivanja. Uzorak sirove ljuske semenki suncokreta samleven je pomoću malog ručnog mlina. Kod materijala nejednolike krupnoće i čestica različitog oblika, kao što
je to slučaj sa ovim uzorkom, srednji ekvivalentni prečnik određuje se sitovnom analizom. Za određivanje nasipne gustine izmerena je
masa uzorka m, kao i njena nasipna zapremina VBM. Sadržaj vlage u biomasi određen je pomoću uređaja za merenje vlažnosti. U
ovom radu prikazan je metod koji koristi piknometar za merenje poroznosti gde se zapremina čvrste faze uzorka VS određuje merenjem pritiska.
Ključne reči: gustina, nasipna gustina, poroznost, vlažnost, poljoprivredni ostaci, biomasa. pneumatski transport biomase.
INTRODUCTION
Interest in biomass production is growing since it is carbon
neutral and a sustainable resource for energy production (Tumuluru et al., 2014). Agricultural biomass are actualy residues of
annual plants such as: straw, stalks, cobs, shells, pits (Babić, et.
al., 2012). Policy-makers have set ambitious targets to increase
the use of renewable energy. Energy producers have identified
biomass as a potential for fulfillment of this goal, relatively
quickly and cost-effective if it is burned in existing coal-fired
power plants (Neville, 2011). Some engineering chalanges like
handling, transportation, storage and processing, have identified
physical properties of biomass as problem for power producers
(Wright et al., 2006, Knauf and Moniruzzaman, 2004; Sokhansanj et al., 2006; Rentizelas et al., 2009). The structure of agricultural biomass is inhomogeneous and its bulk density and
energy content are low compared to conventional fossil fuels.
The use of biomass for energy is either direct - burning biomass in boilers, or indirect - pellet production or biofuels. In
both cases, one of the ways of manipulating the biomass, and
very often the most convenient, is the pneumatic transport. There
are many reasons why pneumatic transport is used for unloading
and reloading of different materials. For all these applications
Journal on Processing and Energy in Agriculture 18 (2014) 3
the particle size of the material has to be reduced. Reducing the
size of particles is considered to be a significant step in the conversion process (Tumuluru et al., 2014).
Pneumatic transport involves the wide variety of particulate
and granular solid materials in a gas stream. Size and shape of
the particles and their surface roughness depends exclusively
how they were formed. In the case of biomass particles are mainly shells of unequal size, different shape and roughness. Therefore, it is important to adopt an "equivalent particle", which spatial shape will represent all of the particles in the mixture. This is
not an easy task, and the most elegant solution was to adopt
sphere as "equivalent particle".
Nomenclature:
fi - mass of fraction i [%]
h (-) - humidity
m (kg) - mass
p (Pa) - pressure
V (m3)- volume
Greek symbols
 (kg/m3) - density
 (-) - porosity
Subscripts
1 – chamber 1
2 – chamber 2
b – bulk
BM - biomass
C - callibration object
S - solid
ave - average
103
Bukurov, Maša et al. / Determination of Some Physical Properties of Biomass for the Purpose of Pneumatic Transport
MATERIAL AND METHOD
b 
Bulk density, particle size distribution and porosity are three
important and closely related parameters in pneumatic transport.
Porosity  is the ratio of volume of fluid within the area comprised by the material (the difference of bulk volume of biomass
VBM and the volume of the solid phase biomass VS) and bulk volume of material VBM:

VBM  VS
V
1 S
VBM
VBM
(1)
Porosity is a dimensionless property and its size ranges from
0 to 1.
In this paper are investigated physical properties of raw sunflower husks obtained from a household in Vojvodina. The material was stored in a covered indoor storage.
There are a many test standards relating to the bulk solid materials handling [1,2]. Although some of the standards were developed by the individual countries (for example, Austria, Sweden, Germany), the majority of the test standards for biomass
material in EU are still in the developing stage. Some characteristics of solid biomass hinder or prevent the application of the
existing standard test methods. For instance, particles are too
large to use the traditional methods of testing (Jenike method
[1]), or non-homogeneity of biomass aditionaly hinder the use of
conventional tests. Nevertheless, the principles of various commonly used experiments can still be used as the background
knowledge for testing solid biomass fuels. (Wu, et al., 2011).
The particle size distribution in the sample is an important
physical property of solid biomass since it, together with the
moisture content influence the flow properties of the material in
transport and storage systems. The understanding of particle size
distribution will also help to deploy suitable handling and storage equipment (Wu, et al., 2011). The simulations (Hilton, et al.
2009) have shown that altering the shape of a particle by a small
amount can significantly affect the bulk dynamics of a pneumatic conveying system. The change in shape of a particle causes
the packing fraction to change, altering the bulk density of the
particle bed. This, in turn, alters the fluidization velocity and can
cause slugs to become unstable.
A sample of raw sunflower husks was grinded using a small
hand mill. For materials of uneven particle sizes and shapes, as
is the case with the sample, average equivalent diameter can be
determined by sieve analysis. For this purpose were used standard sieves made from wire with a square mesh of dimensions:
0.46 mm, 0.96 mm, 2.75 mm, 4.5 mm and 5.7 mm. The sample
was passed through the sieves, which were shaken for 10 minutes with a low amplitude (approximately 1 cm). A series of
five vertically arranged and connected frames enabled the preparation of 6 fractions. Each of the fractions was measured, and the
total mass was obtained as mass share of each of the fractions
mi . Sieve analyzes provided information on participation of
each fraction fi in the total mass of material m.
mi
(2)
fi 
100 [%] .
m
According to cumulative distribution N(d) and density function n(d) was determined average diameter of equivalent particle
dave;
d ave



0
n(d )  d  d (d )
N
[mm].
(3)
Bulk density was determined by measuring sample mass m
and bulk volume VBM:
104
m  kg 
VBM  m3 
(4)
The mass was measured on laboratory scale and bulk volume
in menzura. A series of four measurements was conducted and
finally was calculated mean bulk density.
The moisture content of the biomass was determined with
the device for moisture measurement according to "oven dry"
method [3].
There are various methods in the literature for the porosity
determination. It is known that the porosity of the grains of different cereals (Chang, 1988), sediments, as well as various filters
(Sreedhara, et al., 2014), can be measured by a gas pycnometer
(Chang, 1988). This paper describes a method that uses pycnometer to measure porosity, where the volume of the solid phase
of the sample VS is determined by pressure measuring.
The gas pycnometer is a device which consists of two chambers with a valve between. The measurements consist of three
stages. In each stage are measured pressures in two different
cases. In the first case (Fig. 1), the measurement is performed as
follows: valve 6 between the source of compressed air (compressor) 5 and chamber 2 is closed, valve 4 between chambers 1 and
2 is opened. Chambers 1 and 2 are initially at atmospheric pressure p1 (valve 3 between the chamber and ambient is open).
Valve 4 between the chambers is closed. Valve 6 between the
compressor 5 and chamber 2 (volume V2) is opened. Valve 6 between two chambers and compressor 5 is closed and pressure p2
is measured. It is considered that the chambers and their contents
are at the same temperature T. In the second case, the measurement is performed when the valve 3 between chamber 1 and ambient is closed and valve 4 between chambers 1 and 2 is opened.
Gas flows between the chamber and soon is reached pressure
equilibrium which is measured (p3).
In the second stage of the measurement the same procedure
is repeated. The only difference is that inside the chamber 1 (volume V1) is put biomass 8 with known bulk volume VBM and unknown volume of the solid phase VS (Fig. 2). Pressures p5 and p6
are measured. In the third stage, again the procedure is repeated,
but in the chamber 1 is now put calibration object 9 with known
volume VC (Fig. 3). Pressures p8 and p9 are measured.
Fig.1. First stage of measurments
Fig. 2. Second stage of measurments;
in chamber 1 is put biomass
Fig. 3. Third stage of measurments;
in chamber 1 is put calibration object
Applying ideal gas equation of state and equation of isotherm, following equations are:
Journal on Processing and Energy in Agriculture 18 (2014) 3
Bukurov, Maša et al. / Determination of Some Physical Properties of Biomass for the Purpose of Pneumatic Transport
p3
V1
p2  p3
p  p6
VBM  V1  5
V2
p6
VC
V1 
p8  p9
p3
1
p9
p2  p3
Porosity is calculated according to formula (1).
(5)
V2 
(6)
(7)
RESULTS AND DISCUSION
The results of investigation of physical characteristics of raw
sunflower husks are presented in tables. In Table 1 are presented
results of sample bulk volume determination. In Table 2 is presented sample mass distribution. In Table 3 is presented porosity
of sample. In Table 4 are given physical properties of sample,
such as: average bulk volume, humidity, bulk mass, bulk density
and average porosity.
I
230
II
225
III
220
Ave. bulk
Moisture
Bulk mass Bulk density Average
volume Vbave [ml] Content h [%] mb [g]
b [kg/m3] porosity [-]
225
15.37
43.63
194
0.764
IV
225
Table 2. Sample mass distribution
Diameter 0 - 0.46 0.46-0.96 0.96-2.75 2.75-4.5 4.5-5.7 5.7-10 Total
range of
particle
[mm]
Mass of
0.8
4.03
20.90
15.56 1.24
1.1 43.63
particles
mi [g]
mass of
fraction i
f i [-]
1.83
Number of 19429
particles
Ni [-]
Particle 42237
distribution
ni [-]
9.23
47.9
35.6
2.84
2.52
100
10768
2375
403
16
13
33004
17322
4688
1127
323
16
-
Table 3. Porosity of sample
p2 [Pa]
p3 [Pa]
p5 [Pa]
p6 [Pa]
p8 [Pa]
p9 [Pa]
VC [cm3]
Vb [cm3]
V1 [cm3]
V2 [cm3]
Vs [cm3]
 [-]
2.18
1.13
2.17
1.16
2.17
1.13
3.808
70
399.9
430.3
25.18
0.64
2.26
1.17
2.26
1.2
2.26
1.18
3.808
70
216.7
232.6
11.23
0.839
Although, the value which was calculated with this method
can be used as an input data for the needs of pneumatic conveying and combustion calculation.
Table 4. Physical properties of sample
Table 1. Bulk volume of sample
No. of measuring
Bulk volume Vb [ml]
Fig. 4. Particles distribution of sample
2.17
1.12
2.16
1.15
2.17
1.13
3.808
70
208.2
222.1
13.15
0.812
2.17
1.12
2.16
1.15
2.17
1.13
3.808
70
208.2
222.1
13.15
0.812
It can be noted that particle distribution of sample corresponds to log - normal distribution what was expected (Fig. 4).
Average particle diameter is determined according to Eq. (3) and
it is dave=1.32 mm. This diameter should be used for calculations
as a diameter of equivalent particle.
According to measured data of bulk volume and porosity it
can be concluded that more measuring points should be provided, since the repeatability of measuring is not high enough.
Journal on Processing and Energy in Agriculture 18 (2014) 3
Porosity should be given together with particle size distribution and bulk density, otherwise information on porosity is not
complete.
CONCLUSION
In this paper are presented methods for determining the parameters that describe the biomass sample and that are necessary
in any calculation (pneumatic transport, calculations of combustion). In order to determine physical parameters of the biomass it
had to be grinded first. Than, its bulk volume, bulk density, size
distribution of particles, porosity and moisture content were determined. In this way all the necessary parameters that are included in the calculations of pneumatic transport or combustion
are provided.
The average diameter of equivalent particle was determined
according to particle size distribution. This average diameter is a
baseline information for pneumatic transport or biomass combustion calculation.
Finding porosity is the most complex part of the physical
properties determination. Presented method is easy to use although the apparatus requires some specific features characteristic for pressurized air. The data can be easily processed and together with the bulk density and particle size distribution
represent valid data for calculation.
The bad repeatability of the results indicates that a larger
number of measurements is required in order to get more accurate calculation of arithmetic mean of bulk density and porosity
of the sample.
ACKNOWLEDGMENT:The paper is the result of the project
titled " Integrated and organic fruit and vegetable products drying by combined technology" (Project No TR31058) funded by
the Ministry of Education and Science of the Republic of Serbia.
REFERENCES
Babić, Ljiljana, Radojčin, M., Babić, M., Pavkov, I., MehandžićStanišić, Sanja (2012). Mechanical properties of sunflower
(Helianthus Annuus L.): Fruit affected by different hybrids,
Journal on Processing and Energy in Agriculture, 16 (3), 93-97.
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Tumuluru, J. S., Tabil, L. G., Song, Y., Iroba, K. L., Meda, V.
(2014). Grinding energy and physical properties of chopped
and hammer-milled barley, wheat, oat and canola straws,
Biomass and Bioenergy 60, 58-67.
Wu, M. R., Schott, D. L., Lodewijks, G. (2011). Physical
properties of solid biomass, Biomass and Bioenergy 35, 20932105.
Wright, C. T., Pryfogle, P. A., Stevens, N. A., Hess, J. R.,
Radke, C. W. (2006). Value of distributed preprocessing of
biomass feedstocks to a biorefinery industry. Paper No.
066151. St. Joseph, Michigan, USA: ASABE.
Knauf, M., Moniruzzaman, M. (20014) Lignocellulosic biomass
processing: a perspective. Int Sugar J, 106 (1263), 147-50.
Sokhansanj, S., Kumar, A., Turhollow, F.A. (2006).
Development and implementation of integrated biomass supply
analysis and logistics model (IBSAL), Biomass Bioenergy, 30
(10), 838-47.
Rentizelas, A. A., Tolis, A. J., Tatsiopoulos, I. P. (2009).
Logistics issues of biomass: the storage problem and the multibiomass supply chain, Renew Sust Energ Rev, 13(4), 887-94.
Sreedhara, S. S., Tata, R. T. (2013). A Novel Method for
Measurement of Porosity in Nanofiber Mat using Pycnometer
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in Filtration, Journal of Engineered Fibers and Fabrics 132
http://www.jeffjournal.org Volume 8, Issue 4 – 2013
Hilton, J. E., Cleary, P. W. (2009). The Role of Particle Shape
in Pneumatic Conveying, Seventh International Conference on
CFD in the Minerals and Process Industries CSIRO,
Melbourne, Australi.
Chang, C. S. (1988). Measuring density and Prorsity of Grain,
Kernels Using a Gas Pycnometer, Cereal Chem. 65(1),13-15.
Neville, A. (2011). Biomass Cofiring: A Promising New
Generation Option, Power, 155 (4), 52-6.
Standards
American Society for Testing and Materials. ASTM D6128-06.
Standard test method for shear testing of bulk solids using the
Jenike shear cell; 2006.
American Society for Testing and Materials. ASTM D6773-08.
Standard test method for bulk solids using Schulze ring shear
tester; 2008.
European Committee for Standardization. CEN/TS 335 Solid
biofuels-Methods for determination of moisture content oven
dry method-part 1: total moisture-reference method; 2004
Received: 28. 03. 2014.
Accepted: 30. 03. 2014.
Journal on Processing and Energy in Agriculture 18 (2014) 3
Biblid: 1821-4487 (2014) 18; 3; p 107-110
UDK: 546.217:551.571:621.3.017
Original Scientific Paper
Originalni naučni rad
UNIFORMITY OF AIR TEMPERATURE AND RELATIVE HUMIDITY
INSIDE AND OUTSIDE THE DIFFERENT TYPES OF GREENHOUSES
DISTRIBUCIJA TEMPERATURE I RELATIVNE VLAŽNOSTI
VAZDUHA UNUTAR OBJEKATA ZAŠTIĆENOG PROSTORA
RAZLIČITE KONSTRUKCIJE
Aleksandra DIMITRIJEVIĆ*, Anđelko BAJKIN**, Slobodan BLAŽIN***, Dragan BLAŽIN***
*
Universitz of Belgrade, Faculty of Agriculture, Belgrade, Nemanjina 6, Serbia
**
University of Novi Sad, Faculty of Agriculture, 21000 Novi Sad, Trg Dositeja Obradovića 8, Serbia
***
Agricultural High School Josif Pančić, Pančevo, Serbia
e-mail: [email protected]
ABSTRACT
Greenhouse plant production is one of the most intensive parts of the agricultural production. In order to reduce the costs and
save the energy, various greenhouse constructions and different coverings are offered to the farmers. One of the biggest problems is
in winter production when additional heating and light are needed as well as in summer when intensive cooling is needed. During
these period construction and coverings fully show their qualities. The aim of this research was to investigate the temperature and air
relative humidity distribution in the different greenhouse constructions in the different production systems in order to see if the choice
of the greenhouse construction can improve the production conditions inside the greenhouse enabling the better energy efficiency and
lower energy input for heating / cooling. Air temperature and relative humidity were tracked in the open field and in the two types of
greenhouses (tunnel and gutter connected type) in the lettuce and tomato production.Results show that temperature pattern and its
values during the night and day depend on the greenhouse construction, plant specie that is grown and production season. Gutter
connected type of construction showed more uniform production conditions inside the greenhouse. In the winter production conditions temperature oscillations were not significant and were lower compared to the values measured in the tunnel construction type
greenhouse.
Key words: tunnel, gutter-connected greenhouse, air temperature, air relative humidity, lettuce, tomato.
REZIME
Proizvodnja u zaštićenom prostoru je jedna od najintenzivnijih grana poljoprivredne proizvodnje u smislu potrošnje energije i
ostvarenog prinosa. Na tržištu je veliki broj pokrivnih materijala i materijala konstrukcije kojima se može uštedeti energija i time
povećati energetska efikasnost proizvodnje u zaštićenom prostoru. Jedan od značajnijih problema koji se javlja kod ovog vida proizvodnje su nepovoljni temperaturni uslovi tokom zimskog i letnjeg perioda. Pravilnim izborom konstrukcije, pokrivnog materijala i
orijentacije objekta nepovoljni uticaji niskih temperatura tokom zime i visokih temperatura tokom leta, se mogu ublažiti. Cilj ovog
rada je bila analiza temperaturnih i uslova relativne vlažnosti vazduha u objektima zaštićenog prostora različite konstrukcije u proizvodnji salate i paradajza kako bi se videlo da li se izborom konstrukcije objekta zaštićenog prostora može uticati na ravnomernost
proizvodnih uslova u objektima, i samim tim, na kvalitet proizvodnje i ostvareni prinos. Prema navedenom cilju, temperatura i relativna vlažnost vazduha su praćeni unutar objekta (njegovom dužinom i visinom) i izvan objekta, tokom proizvodnje zelene salate i paradajza. U istraživanje su bila uključena dva objekta zaštićenog prostora, i to tunel i dvobrodni plastenik. Rezultati ukazuju na postojanje razlika u rasporedu temperature i relativne vlažnosti vazduha unutar objekata različite konstrukcije. Blok objekat se pokazao
kao sredina sa uniformnim rasporedom temperature i relativne vlažnosti dužinom objekta tokom čitavog dana. U zimskom periodu su
oscilacije temperature bile manje značajne nego kod objekta tunel tipa.
Ključne reči: tunel, blok objekat, temperatura vazduha, relativna vlažnost vazduha, zelena salata, paradajz.
INTRODUCTION
Factors that determine the greenhouse production system are
air temperature, relative humidity of air and soil, air quality and
light conditions. Tracking these micro-climatic conditions is of a
great importance for the successful greenhouse production (Ponjičan et al., 2011, Babić et a.l, 2004, Karadžić, 2005).
Various types of greenhouse constructions and covering materials are available at the market and are offered to the farmer
(Dimitrijević et al., 2011). Purpose of tracking the greenhouse
production continuously is to optimize the plant productions in
the greenhouse. It is necessary to know the correlation between
greenhouse construction, covering material and type of the plant
production.
Temperature conditions in the greenhouses influence the
overall plant growth, yield and fruit quality. If the air temperature and relative humidity in the greenhouse are lower than op-
Journal on Processing and Energy in Agriculture 18 (2014) 3
timal plants will be shorter with smaller dark green leaves. In the
case of lower temperature and higher relative air humidity flowering of the plants will be delayed and the yield will be lower.
Higher night temperatures cause the higher consumption of organic matter by plants which grow with the long pale green gently leaves with the lower yield and deformed fruits. It is stated
(Lazić Branka et al., 2001, Hanan, 1998, Nelson, 2003) that
night temperatures and the temperatures during the day should
be 3–5° C lower compared outside temperatures during the
sunny days. It is also stated that temperature variations during
the day should not be more than 2 do 3° C. Literature sources
(Lazić Branka et al., 2001, Hanan, 1998, Nelson, 2003, Sengar
and Kothari, 2008, Singh and Tiwari, 2000) confirm the statement that temperature in greenhouses varies along their length,
width and height. The pattern of this variation is influenced by
the greenhouse type of construction and its dimensions, covering
material, orientation and applied heating and venting systems.
107
Dimitrijević, Aleksandra et al./Uniformity of Air Temp. and Relative Hum. Inside and Outside the Different Types of Greenhouses
The aim of this paper was to show how the type of greenhouse construction, production season and plant species can influence the uniformity of the micro-climatic conditions in the
greenhouses.
MATERIAL AND METHOD
3.2 m
For the purpose of the research a tunnel type (TUN) 5.5 x 24
m covered with 180 µm PE UV IR outside folia (Figure 1) and a
gutter connected plastic covered greenhouse (GUT) 21 x 250 m
and with 50 µm inner folia and 180 µm outside folia were used.
24 m
6.5 m
4.2 m
5.5 m
ture was observed in the central part, while in the afternoon
hours the highest temperature was measured in the south part of
the greenhouse while the lowest was measured in the north part.
Statistical analysis of the data showed that temperature differences along the greenhouse during the night are not significant.
The LSD test (0.05 and 0.01 significant level) of the morning
temperatures showed that there is a very significant difference in
the temperatures along the greenhouse (Fig. 2). These values
were 2.05 °C and 2.74 °C for the given levels of significance.
Temperature difference of 2.63 °C between the south and the
central part of greenhouses showed to be significant. Variation
coefficient was 10.82 % and standard deviation 1.11 °C. Measurements in the 13h also showed variations in the temperature
along the tunnel greenhouse. Temperature was highest in the
south part and lowest in the north part (Tab. 1). Variance analysis confirmed that these differences are significant and based on
the LSD test it was concluded that difference of 5.13 °C between
south and central part was significant and that difference of 6.91
°C between south and north side was very significant (Fig. 2).
Variation coefficient was 8.32 % while standard deviation was
2.93 °C.
Table 1. Temperature variation inside and outside the
greenhouses in the lettuce production
Time of the day
1h
7h
13h
19h
TUN GUT TUN GUT TUN GUT TUN GUT
2 x 10.5 m
Fig. 1. Tunnel and gutter connected greenhouses
Production surface of the tunnel greenhouse was 132 m2,
covering material / production area ratio was 19.91 and its specific volume was 12.56 m3/m. Gutter-connected greenhouse had
the 5250 m2 production surface, covering material / production
surface ratio 1.62 and specific volume of 37.92 m3/m. Experiment was carried out at the private property in Pancevo and at a
private property near Jagodina (Serbia).
Temperature and air humidity were measured using the sets
of
WatchDog
Data
loggers
150
Temp/RH,
t= 0.6 °C and RH= 3 % and a WatchDog Data Logger Model
450 – Temp, Relative Humidity - Temp/RH, t= 0.6 °C and RH=
3 %. In the tunnel greenhouse, lettuce production conditions
were analysed for the October 2008 production season while tomato production conditions were analysed for the summer 2008
production season. In the gutter connected greenhouse lettuce
production conditions were analysed for the winter 2008/09 production season while tomato production was analysed for the
summer 2008 production season. Both of the greenhouses were
without heating systems.
Statistical analysis of the results was based on variance
analysis, F tests and LZD tests which were used to determine if
the temperature and relative humidity are uniform along the
greenhouses and if the type of construction and plant specie influence the temperature and relative humidity uniformity. Data
used for the analysis represent the five days average values.
RESULTS AND DISCUSSION
Temperature distribution
According to some authors (Enoch, 1978, Hanan, 1998, Nelson, 2003) tunnel greenhouses are considered to be the simplest
form of the greenhouses in which temperature and the other production parameters vary during the day significantly depending
on the outside climatic parameters.
Temperature measurements in the tunnel greenhouse show
that temperature varies along the greenhouse. During the night it
was highest on the north side and lowest on the south side of the
greenhouse (Tab. 1). In the morning hours the highest tempera-
108
INSIDE
North side
Centre part
South side
Average
OUTSIDE
Inside/outside
difference
9.21
8.88
8.87
8.99
8.66
0.85
1.31
3.41
1.86
-2.63
9.15
11.78
9.85
10.26
10.28
2.46
2.69
3.36
2.84
-2.25
32.32
34.10
39.23
35.22
22.84
15.05
15.67
13.12
14.61
14.64
13.18
12.10
12.55
12.61
15.46
1.79
2.35
4.88
3.01
-1.52
0.33 4.49 -0.02 5.09 12.38 -0.03 -2.85 4.53
Measurements in 19h (Tab.1) show that the north part had
the highest temperature and the central part had the lowest temperature. Variance analysis showed that these are significant differences and the LSD test showed that the difference of 1.08 °C
was significant between north and central part. Coefficient of
variation was 3.49 % and standard deviation 0.44 °C. It can be
concluded that in the case of lettuce production in the tunnel
greenhouse one could expect significant temperature variation
along its length during the day.
Statistical analysis for testing the mean values showed that
there are differences between inside and outside temperature in
the tunnel structure and that these differences are very significant in the afternoon hours (Fig. 3). This means that during the
night and early morning hours one should not expect significantly higher temperatures inside the greenhouse compared to the
outside temperatures.
1h Δt=0.350 C
7h Δt=2.630 C *
13h Δt=6.910 C **
19h Δt=1.080 C *
Maximum daily Δt= 30.360 C
1h Δt=0.830 C
7h Δt=1.260 C
13h Δt=2.30 C
19h Δt=2.620 C
Maximum daily Δt= 22.760 C
Fig. 2. Temperature variation significance in the tunnel lettuce
and tomato production
In the winter vegetable production the most critical are the
temperatures during the night. Temperature measurements in the
gutter-connected greenhouse in lettuce production show variations during the day and along the greenhouse. The lowest temperature was observed during the night in the north part of the
greenhouse (Tab. 1). Statistical analysis showed that temperature
does not vary significantly along the greenhouse in the night.
Journal on Processing and Energy in Agriculture 18 (2014) 3
Dimitrijević, Aleksandra et al./Uniformity of Air Temp. and Relative Hum. Inside and Outside the Different Types of Greenhouses
Variation coefficient was 59.68% while standard deviation was
1.11 °C. The same situation was observed for all other measuring periods (Fig. 4). This means that in the gutter-connected
greenhouse temperature does not vary significantly along its
length which means that in the case of winter lettuce production
more uniform temperature conditions can be expected in the gutter-connected greenhouses compared to the tunnel structures.
Concerning the fact that both type of greenhouses had the same
covering material, with the same period of exploitation the reasons for these differences in the temperature uniformity distribution can be searched in the type of construction, its volume and
orientation. Tunnel greenhouse is a single span type of greenhouse with the specific volume of 12.56 m3/m and covering material / production surface ratio of 1.91 while gutter-connected
greenhouse is a type of multi-span greenhouse with the specific
volume of 37.91 m3/m and covering material / production surface ratio of 1.62. It is stated (Nelson, 2003, Hanan, 1998) that
the smaller is the ratio covering material / production surface the
smaller is the surface of the greenhouse that is exposed to the
weather and thus are the heating requirements lower because the
temperature conditions in the greenhouses are more uniform.
The other parameter that can be responsible for the temperature
oscillation is the greenhouse orientation. Single span greenhouses in this region should be orientated north-south but in this case
the orientation was east-west.
1h Δt=0.830 C
7h Δt=0.020 C
13h Δt=12.380 C **
19h Δt=2.850 C **
1h Δt=1.250 C
7h Δt=7.640 C **
13h Δt=8.310 C **
19h Δt=2.160 C
Fig. 3. Outside / inside tunnel temperature differences in lettuce
and tomato production
Measurements of the outside temperature (Tab. 1) showed
that the temperature in the greenhouse was significantly higher
compared to the outside during the day as well as during the
night (Fig. 5). During the night temperature was up to 5.47 °C
higher compared to the temperature outside the greenhouse. During the days these differences are even higher (up to 18.83 °C at
13h). When inside and outside temperature patterns are analysed
it can be concluded that the gutter-connected greenhouse is well
thermally balanced. Inside temperature is stabile and does not
vary much during the day and along the greenhouse length
enabling to all the plants in the greenhouse to have the same
production conditions.
1h Δt=2.560 C
7h Δt=0.9 0 C
13h Δt=2.550 C
19h Δt=3.090 C
Maximum daily Δt= 4.820 C
1h Δt=0.320 C
7h Δt=0.190 C
13h Δt=0.190 C
19h Δt=1.330 C
Maximum daily Δt= 25.960 C
Fig. 4. Temperature variation significance in the gutterconnected lettuce and tomato production
1h Δt=4.220 C **
7h Δt=5.090 C **
13h Δt=13.790 C **
19h Δt=4.530 C *
1h Δt=1.890 C
7h Δt=4.970 C **
13h Δt=12.690 C **
19h Δt=0.310 C
Fig. 5. Outside / inside gutter-connected temperature differences
in lettuce and tomato production
In the summer greenhouse vegetable production it is important to have good ventilation systems that will lower the temperature in the greenhouses and that will eliminate parts of the
greenhouses with high temperature. Temperature measurements
in the tunnel and gutter-connected greenhouse show that the
Journal on Processing and Energy in Agriculture 18 (2014) 3
temperature varies during the day (Fig. 2 and Fig. 4), being the
lowest in the night and the highest in the noon, as well along the
greenhouses (Tab. 2) being in most of the cases the highest in
the central part of the greenhouses.
Table 2. Temperature variation inside and outside the
greenhouses in the tomato production
Time of the day
1h
7h
13h
19h
TUN GUT TUN GUT TUN GUT TUN GUT
INSIDE
North side
Centre part
South side
Average
OUTSIDE
Inside/outside
difference
15.80
16.63
16.10
16.07
14.93
17.67
17.99
17.84
17.83
17.83
22.87
23.05
24.13
23.32
15.71
22.42
22.54
22.35
22.44
17.46
37.26
38.56
36.26
37.36
29.05
42.55
43.63
42.44
42.87
30.18
25.35
27.97
26.20
26.51
24.35
24.86
23.50
23.51
23.96
23.95
1.14
0
7.61
4.98
8.31 12.69 2.16
0.01
The exception was the tunnel structure in the morning hours
where south side was with the higher temperature and the gutterconnected greenhouse in the afternoon hours where north part of
greenhouse had the higher temperature.
As for the differences in the greenhouses inside and outside
temperatures the results have the similar tendencies for the tunnel and gutter-connected greenhouse. In both cases temperature
differences appear to be significant in the early morning hours
and in the noon (Fig. 3 and Fig. 5). In case of tunnel greenhouse
the temperature difference in the 7 h was up to 11.07 °C and statistical analysis showed that these differences were very significant. The similar results were obtained for the measurement in
13h. The differences were up to 13.18 °C and, after statistical
analysis, showed to be very significant. In the gutter-connected
greenhouse similar results were obtained. Temperature differences during the night and in the evening were not statistically
significant. Measurements in 7 h showed that temperature in the
greenhouse was up to 11.35 °C higher compared to the outside
temperatures. Statistical analysis showed that the differences of
3.37 °C can be considered as very significant. Measurements in
13 h show that temperature inside the greenhouse was up to
22.16 °C higher compared to the outside temperature. Statistical
analysis showed that temperature difference of 5.02 °C can be
considered as very significant.
In this way it can be concluded that in the summer tomato
production in the tunnel and gutter-connected greenhouse temperature conditions in the greenhouses do not vary much along
the greenhouse length. Significant differences were only observed in the inside and outside temperatures in both greenhouses in the early morning hours and at noon. Concerning the temperature values, these oscillations can be considered as acceptable.
Relative humidity distribution
Relative humidity is a very important factor of plant growth
and development because it influences plant transpiration, photosynthesis and disease risks. Different plants have a different
demand concerning the air relative humidity. Optimal relative
humidity for cucumber is very high (90 - 95%) while for the tomato it is 50 - 65%. Literature (Lazić Branka et al., 2001,
Hanan, 1998, Nelson, 2003, Sengar and Kothari, 2008, Singh
and Tiwari, 2000) states that air humidity varies during the day
and along the greenhouse length and height. It is stated that the
pattern of variation depends on greenhouse type of construction
its dimensions, covering material and the plant specie that is
produced in the greenhouse.
In the tunnel lettuce production, relative humidity measurements showed that there are differences between outside and in-
109
Dimitrijević, Aleksandra et al./Uniformity of Air Temp. and Relative Hum. Inside and Outside the Different Types of Greenhouses
side values as well as differences in the greenhouse during the
day. Results show that relative air humidity inside the greenhouse is higher through the day if compared to the outside. Statistical analysis showed that differences between inside and outside relative air humidity were very significant in the early
morning hours, in the evening and in the night (Fig. 6). In the
early morning the differences were up to 68.97% and 52.69%
difference was considered to be very significant. In the evening
the difference of 53.2% was considered as very significant. In
the night the average difference was 55.71% and was considered
to be very significant.
1h ΔRH=55.71% **
7h ΔRH=52.69% **
13h ΔRH=2.49%
19h ΔRH=53.2% **
1h ΔRH=29.4% **
7h ΔRH=22.81% **
13h ΔRH=2.44%
19h ΔRH=31.61% **
Fig. 6. Outside / inside tunnel air relative humidity differences in
lettuce and tomato production
This result was expected taking into account the plant respiration that, as a consequence, has production of heat, water and
CO2. Since no ventilation was applied, because of the temperature uniformity, the relative humidity in the tunnel was growing
higher up till early morning hours.
Measurements of the relative air humidity in the gutterconnected greenhouse show that great care must be taken into
account when choosing the type of greenhouse construction.
Like in the case of tunnel construction, air relative humidity in
the greenhouse show variations compared to the outside relative
air humidity. Statistical analysis of the obtained data shows that
these differences are not significant (Fig. 7). During the night
hours air relative humidity was even lower inside the greenhouse. In average it was 6.52% lower. In the early morning
hours air relative humidity was higher inside the greenhouse. In
average the difference was 3.68% higher and it was considered
not to be significant. Measurements show that in 13h relative air
humidity was higher outside the greenhouse. Again, in the afternoon, air in the greenhouse had higher relative humidity.
1h ΔRH=6.52%
7h ΔRH=3.86%
13h ΔRH=2.56%
19h ΔRH=3.24%
1h ΔRH=31.59% *
7h ΔRH=25.49% **
13h ΔRH=1.5%
19h ΔRH=24.92% *
Fig. 7. Outside / inside gutter-connected greenhouse air relative
humidity differences in lettuce and tomato production
Gutter-connected greenhouse has showed to be beneficial in
the case of tomato production since tomato plants are not adjusted to the higher values of air relative humidity. In the tunnel
greenhouse air relative humidity was higher through the day and
night compared with the outside air relative humidity. Statistical
analysis of the obtained data (Fig. 7) shows that these differences were all very significant except in the midday period. During
the night the differences in the air relative humidity were up to
37.4%. In the early morning hours these differences were up to
31.3%. In the middle of the day the differences were the lowest
and were up to 3.29%. In the afternoon hours air relative humidity inside the tunnel rose and the differences were up to 43.99%.
In the gutter-connected greenhouse there was the same tendency
but the differences between inside and the outside air relative
humidity were smaller. Again the differences were significant in
the afternoon hours and during the night. In the early morning
hours the differences were the highest (up to 39.33%) and were,
statistically, considered to be very significant.
110
CONSLUSION
Obtained results show that micro-climatic conditions in the
greenhouse vary during the day and along the greenhouse length.
The variation pattern depends on the greenhouse type of construction, its orientation, plant production season and type of
plant production. Generally it can be concluded that regarding
the both lettuce and tomato production tunnel greenhouse construction can not be recommended as an optimal choice. Its specific volume was 12.56 m3/m while covering material / production surface ratio was 1.91. In the winter it does not provide significantly higher temperatures inside the greenhouse. Also the
temperature conditions inside the greenhouse are not uniform
and stabile. In the summer production higher air relative humidity brings the risk of introduction of plant diseases. On the other
side gutter-connected greenhouse, having the specific volume of
37.92 m3/m and covering material / production surface ratio of
1.62, in the winter production conditions provides more uniform
temperature inside the greenhouse and provides significantly
higher temperatures during the day. In the summer production
variation of the temperatures were observed only in the midday
section. Relative humidity inside the greenhouse was higher but
the differences were much lower compared to the differences
obtained in the tunnel structure.
ACKNOWLEDGEMENT: The authors wish to
thank to the Ministry of education and science of
Republic of Serbia for financing the TR 31051
Project.
REFERENCES
Babić, M., Babić, Ljiljana, Karadžić, B., Pavkov, I., Ponjičan, O.
(2004). Povoljna mikroklima u grejanom plasteniku kao uslov
kvalitetna proizvodnje. Journal on Processing and Energy in
Agriculture (former PTEP), 8 (3-4), 61-64.
Dimitrijević, Aleksandra, Bajkin, A., Đević, M., Urošević, M.
(2011). Energetska produktivnost proizvodnje paradajza u
objektima zaštićenog prostora. Journal on Processing and
Energy in Agriculture (former PTEP), 15 (3), 138-142.
Enoch, H.Z. (1978). A theory for optimalization of primary
production in protected cultivation, I Influence of aerial
environment upon primary plant production, Symposium on
More Profitable use of Energy in Protected Cultivation,
Sweden.
Hanan, J.J. (1998). Greenhouses – Advanced Technology for
Protected Horticulture, CRC Press, Boca Raton, USA.
Karadzic, B. (2005). Koncepcije sistema upravljanja klimom
plastenika. Journal on Processing and Energy in Agriculture
(former PTEP), 9 (3-4), 74-78.
Lazić, Branka, Marković, V., Đurovka, M., Ilin, Ž. (2001).
Povrće iz plastenika, Beograd.
Nelson, P.V. (2003). Greenhouse Oparation and management,
Sixth Edition, Prentice Hall, New Jersey.
Ponjičan, O, Bajkin, A, Dimitrijević, Aleksandra, Mileusnic, Z.
Miodragović, R. (2011): The influence of Soil Mulching and
Greenhouse Covering Material on the Temperature
Distribution in Lettuce Production, Actual Tasks on
Agricultural Engineering, Proceedings of the 39. International
Symposium on Agricultural Engineering, Opatija, Croatia, p.
393-401, ISSN 1333-2651.
Sengar, S. H., Kothari, S. (2008). Thermal modeling and
performance evaluation of arch shape greenhouse for nursery
raising. African Journal of Mathematics and Computer Science
Research 1(1), 1–9.
Singh, R.D., Tiwari, G.N. (2000). Thermal heating of controlled
environment greenhouse: a transient analysis. Energy
Conversion and Management, 41, 505–522.
Received: 12. 03. 2014.
Accepted: 28. 03. 2014.
Journal on Processing and Energy in Agriculture 18 (2014) 3
Biblid: 1821-4487 (2014) 18; 3; p 111-114
UDK: 621.86
Original Scientific Paper
Originalni naučni rad
UTILIZATION OF SCREW CONVEYOR AS PRE-MIXER:
DISCRETE ELEMENT MODEL
KORIŠĆENJE PUŽNOG TRANSPORTERA KAO PREDMEŠAČA:
MODEL DISKRETNIH ELEMENATA
Aca JOVANOVIĆ*, Milada PEZO**, Lato PEZO*, Sanja STANOJLOVIĆ*,
Biljana LONČAR***, Milica NIĆETIN***, Ljubinko LEVIĆ***
*
University of Belgrade, Institute of General and Physical Chemistry, 11000 Belgrade,Studentski trg 12/V, Serbia
**
University of Belgrade, Institute of Nuclear Sciences Vinča, Laboratory for Thermal Engineering and Energy,
11001 Belgrade, P. O. Box 522, Serbia
***
University of Novi Sad, Faculty of Technology, 21000 Novi Sad, Bulevar Cara Lazara 1, Serbia
e-mail: [email protected]
ABSTRACT
Single pitch screw conveyors are commonly used equipment in industry, used for transport of bulk materials. In this paper, several horizontal single-pitch screw conveyors with modifications in helices geometry were investigated for mixing action during transport, using Discrete Element Method. The influence of geometry variations on the performance of screw conveyor was examined, different designs were compared, and their effects on mixing performances were investigated. During the transport, the particle tumbles
down from the top of the helix to the next free surface and that segment of the path was used for auxiliary mixing action. According to
results, the addition of three complementary helices or blades, oriented in the same, or the opposite direction of screw helix, enlarges
the particle path within the screw conveyor 3 - 5 times.
Key words: Screw conveyor, Transport, Pre-mixer, Discrete Element Model.
REZIME
Pužni transporteri su dobro poznata procesna oprema, koja se veoma intenzivno koristi u različitim granama industrije, uglavnom za podizanje i/ili transport rasutih materijala na kratkim i srednjim rastojanjima. Pužni transporteri se koriste u proizvodnji i
preradi hrane, u industriji plastike, preradi mineralnih sirovina, u poljoprivrednoj proizvodnji kao i u prerađivačkoj industriji. Uprkos veoma jednostavnoj konstrukciji, sam transport materijala pužnim transporterom je veoma složen za razumevanje i optimizaciju
(korišćenjem matematičkih modela) i konstruktori se veoma često oslanjaju na iskustvene podatke pri konstruisanju i izradi. U ovom
radu je opisano nekoliko horizontalnih puževa, konstantne dužine koraka puža, sa izvesnim izmenama u geometriji pužnih spirala,
kod kojih su testirane mogućnosti mešanja tokom transporta materijala, korišćenjem „Metode diskretnih elemenata“.Ispitivani su
uticaji ovih izmena u geometriji na transportne performanse pužnog transportera, različita konstrukciona rešenja su međusobno
poređena, kao i efekti ovih izmena u geometriji na mešanje u toku transporta.Tokom transporta u pužnom transporteru, čestice
padaju sa vrha pužne spirale na prvu sledeću slobodnu površinu pužne spirale i taj segment putanje čestice može da bude iskorišćen
za dopunsko mešanje materijala tokom transporta. Putanja čestice se drastično povećava ugradnjom tri dodatne zavojne površine
usmerene u isom pravcu kao i pužna spirala. Skraćivanjem dodatnih zavojnica, koje su usmerene u istom smeru kao i pužna spirala,
unekoliko se smanjuje putanja čestice (usled prekidanja zavojnice na sredini pužnog transportera). Putanja čestice se produžava,
kada se ugrade dodatne zavojne površine koje su usmerene u suprotnom pravcu od pravca pužne spirale. Ugradnjom tri dodatna
pravolinijske letve, dobijena je najduža putanja čestice.
Ključne reči: pužni transporter, transport, predmešač, model diskretnih elemenata.
INTRODUCTION
Screw conveyors are widely used for process equipment, utilized for transport and/or elevate particles continuously, at controlled rates. A summary of current design methods and problems experienced for screw conveyors can be found in Bortolamasi and Fottner (2001). The description of the theoretical behavior of screw conveyors can be found in articles by Yu and
Arnold (1997), and Roberts (1999). Screw conveyors are also
used for metering (measuring the flow rate) from storage bins
and adding small controlled amounts of trace materials (dosing)
such as pigments to granular materials or powders, (Roberts and
Willis, 1962, Cleary, 1998a, Cleary, 1998b).
Discrete element modeling (DEM), of particulate flow in a
screw conveyor was first reported by Shimizu and Cundall
(2001). They examined the performance of horizontal and vertical screw conveyors and compared their results with previous
Journal on Processing and Energy in Agriculture 18 (2014) 3
work and empirical equations. Owen et al. (2003) introduced the
use of a periodic slice model to explore the performance of a
long screw conveyor. Cleary (2004) used DEM to study draw
down patterns from a hopper by a 45° inclined screw conveyor.
This work was extended by Cleary (2007) to examine the effect
of particle shape on the draw down flow from the hopper and on
the transport characteristics of the screw conveyor.
Screw transporters are frequently used to remove powder or
grain material from silos, and transport it to the mixer. Before
the mixing process is performed, it is often practice that some
premixing action is done, using some type of the auxiliary mixer. The main aim of this paper is to consider the possibility of
prolonging particle transport path from the moment of entering
to the moment of leaving the screw conveyor, with addition of
new elements welded on the helix of screw conveyor, in order to
increase the effect of auxiliary mixing along with the transport of
particles. In this way a screw transporter could be considered as
111
Jovanović, Aca et al. / Utilization of Screw Conveyor as Pre-Mixer:Discrete Element Model
transporter and also the continous pre-mixer. Discrete Element
Method (DEM) was used to explore the modifications in screw
geometry and the influence on transport path, during the transport of just one particle, with the intention to keep the material
flow unspoiled.
ameter of the helical blade. The DEM model was simplified (and
the CPU time is significantly reduced) by applying periodic
boundary conditions to a single pitch of the screw as shown in
Figure 1.
MATERIAL AND METHOD
Model description
DEM simulation involves following the motion of
every particle involved in the model definition, and
modeling each collision: inter-particle and between
z (m)
t (s)
the particles and their environment (e.g. the internal x (m)
y (m)
0.4
0
5
10
15
20
25
surface of the screw casing and the surface of the ro-0.020
0.002
0.3
tating screw). The boundary geometry is built using a
t (s)
0.000
-0.021
0.2
CAD package and imported as a small sized triangu0 5 10 15 20 25
lar surfaces mesh into the DEM package. This pro0.1
0.002
-0.022
vides unlimited flexibility in specifying the three di0.0
0.004
0 5 10 15 20 25
mensional geometries with which the particles intet (s)
ract. Here the particles are modeled as spheres (also
Fig. 1. Standard pitch, single flight screw conveyor, with
as small sized triangular surfaces). The modeling
Cartesian coordinate changes over time t
technique is based on the assumption that the particle
is soft (soft particle method), and that particles are allowed to
The pitch of the screw was 50 mm, the diameter of the screw
overlap. The amount of overlap is labeled as Δx, and the normal shaft was 15 mm, and the blade thickness was approximately 1
and tangential relative velocities determine the collisional forces. mm. The internal diameter for tubular case was 47 mm, giving a
The normal force is considered as the repulsive force that pushes gap of about 1.5 mm between the outer edge of screw blade and
the particles apart (or particle from bounding geometry), de- the internal surface of the casing. Screw conveyor length was
picted as the action of the spring, and also dissipation action, re- 400 mm. All simulations used the same rotational speed of 20
rpm.
sulting in an effective coefficient of restitution, shown as dashDEM particles are modeled as spheres in three dimensions.
pot action. Tangential component is considered as an increment- Small-sized triangular surfaces mesh was used for geometrical
ing spring action and dashpot action that is subject to frictional modeling of seed, (grain that is very close to spherical shape),
limit.
and for the DEM calculation, and the size of the particles used
In this article, DEM analysis was used to investigate the path was 4.0 mm, with a density of 500 kg/m3. The particle–boundary
of single particle, during transport, considering the differences in frictions used for the DEM (base case) simulations were 0.3, and
helix of the screw conveyor. Here applied DEM analysis can be particle–boundary coefficients of restitution were 0.3. The maxsummarized as follows: neighboring interaction list is based on imum overlap between particle and boundary is determined by
the used grid (defined by used triangular surface mesh), and the the normal spring stiffness. Typically, average overlaps of 0.1–
0.5% are desirable, requiring a spring constant of 1000 N/m for
boundary objects (also defined by triangular surface mesh),
this type of simulation.
which are treated as virtual, non-moving particles. The collisionA series of DEM simulations was performed for various
al forces on the specific particle and boundaries are evaluated screw conveyor-mixer geometry. Examined modified screw
efficiently using the neighboring list and the spring-dashpot inte- conveyor-mixers used in this article were:
raction model, (Cleary, 1997). All the forces on the boundary
1. Screw conveyor-mixer with three additional helices
objects and specific particles are summed and the resulting equa- oriented in the same direction as screw transporting helix,
tions of motion are integrated using DEM package. The particle welded on the periphery of the helix, Fig. 2,
2. Screw conveyor-mixer with three additional helices
velocities and their axial and tangential (swirl) components were
oriented
in the opposite direction from transporting helix,
invariant to changes of particle–wall friction.
welded on the periphery of the helix, Fig. 3,
RESULTS AND DISCUSSION
In this work the influence of helix geometry on
single spherical particle trajectory is investigated.
Applied DEM analysis the mutual influence of different configuration of helix geometry and observed
particle is focused to inspect the possibility of prolonging single particle path during transport. The
basic screw conveyor used in this study was a standard pitch, single flight screw conveyor with no additional helices, which is commonly used in
processing industry. The pitch of the screw is defined as the length, along the drive shaft, of one turn
of the helical blade, as shown in Figure 1. A standard pitch screw has its pitch equal to the outer di-
112
x (m)
0.4
0.3
0.2
0.1
0.0
0
y (m)
.
0.01
0.00
-0.01
5
10 15 20 25
t (s)
-0.02
5
10
z (m)
0.02
t (s) 0.01
15 20 25 0.00 0 5
0.01
0.02
t (s)
20 25
Fig. 2. Screw conveyor-mixer with three additional helices
oriented in the same direction as screw blades, with
Cartesian coordinate changes over time t
Journal on Processing and Energy in Agriculture 18 (2014) 3
Jovanović, Aca et al. / Utilization of Screw Conveyor as Pre-Mixer:Discrete Element Model
3. Screw conveyor-mixer with three truncated additional helices oriented in the same direction as transporting helix, welded
on the periphery of the helix, Fig. 4,
4. Screw conveyor-mixer with additional straight line blades,
welded on the periphery of the helix, Fig. 5.
The movement of granular particles, modeled as spheres in
DEM simulation, was observed from the initial moment, the
entering in screw transporter-mixer to the moment of leaving the
all other cases the particle is moving on a much longer path
which was particularly evident in the case of screw conveyormixer with additional straight line blade (Fig. 5).
In case of single flight screw conveyor (Fig. 1), the total particle path is only 397.6 mm, according to DEM simulation. Initial small perturbation was observed, and afterward straight lined
path, caused by screw conveyor transporting action
Screw conveyor-mixer with three additional helices oriented
in the same direction as screw blades (Fig. 2),
strongly enlarges the total particle path, calculating
more than a three times longer trajectory of 1458.2
mm, for equal transport time of 23.5s.
After reaching the top of the screw the particle
x (m)
y (m)
z (m)
t (s) tumbles down from the top of the helix. The par0.02
0.0
ticle tumbling down to the next free surface on the
0.4
t (s) 0.2 0 5 10 15 20 25
heap and that segment of path can be used for aux0.00
5 10 15 20 25 0.4
0.2
iliary mixing action.
-0.02
0.6
When using screw conveyor-mixer with three addi0.0
0.8
0 5 10 15 20 25
-0.04
tional helices oriented in the opposite direction
t (s)
from screw blades (Fig. 3) for transporting and auxFig. 3. Screw conveyor-mixer with three additional helices oriented i
iliary mixing action, transporting path enlarges even
the opposite direction from screw blades, , with
more, to 1764.4 mm, which was expected, because
Cartesian coordinate changes over time t
opposite oriented helices return the single particle a
bit backward, as can be seen from Fig. 3.
external tube, and the motion path was analyzed.
The purpose of this analysis is to improve the
geometry of the standard screw transporter with
additional elements, welded on the perifery of the
helix that enable prolonging of particle path within
z (m)
y (m)
the screw conveyer. It is well known, that the screw x (m)
0.01
0.02
0.4
conveyor fill level should be less than 50%, i. e.
t (s)
0.3
0.01
0.00
much of the volume above the helix blade is empty
0 5 10 15 2025 30 35
t (s)
0.2
0.00
during transport, and this volume can be used for
0 5
30 35 -0.01
0.1
-0.01
additional mixing action during transport. Using
-0.02
0.0
-0.02
DEM simulation of the particle trajectories, single
0 5 10 15 20 25 30 35
t (s)
particle coordinates x = f (t), y = f (t) and z = f (t)
Figure 5. Screw conveyor-mixer with additional straight line blade,, with
have been obtained, and plotted (Fig. 1-5), from the
moment of entering until the moment of leaving the
Cartesian coordinate changes over time t
screw conveyor.
The effect of single path prolonging leads to enhance the inBy truncated additional helices oriented in the same direction
terferences between observed particles and increase probability as screw blades (Fig. 4), particle path is being shortened (due to
of particles being mixed during the transport (in case that screw broken helices at the middle of screw conveyor). In this case,
conveyor is transporting several different components and/or total path is 1728.8 mm.
different particle sizes). The movement of just one single particle
Screw conveyor-mixer with additional straight line blade exhas been observed in order to show possible solutions that would erts the longest single particle path in this simulation (Fig. 5):
increase the particle path by adding elements to the screw 2061.6 mm, which is a less more than five times compared with
conveyor, not changing the basic dimensions of the screw single flight screw conveyor.
conveyor.
In the first case, when the screw transporter works only as a
CONCLUSION
conveyor, particle path is almost a straight line (Fig. 1), while in
Modified geometry screw conveyor, and its utilization in mixing action were analyzed. The transport
action of single particle depends on the geometry of
the helix, and the transporting path can be significantly prolonged by inserting these elements to the
x (m)
y (m)
z (m)
helix of screw transporter. Particle retention time re0.01
0.4
mains constant, but the velocity is significantly in0.01
t (s)
0.3
t
(s)
creased, and the probability of mixing of two or more
0.00
0 5 10 15 20 25 0.00 0 5
20 25 particles is also enhanced, in respect to distance tra0.2
-0.01
-0.01
0.1
veled is much longer. Discrete Element Method
-0.02
-0.02
0.0
(DEM) was used for an investigation of the effects of
0 5 10 15 20 25
t (s)
differences in screw geometry and the influence on
Fig. 4. Screw conveyor-mixer with three truncated additional helices oriented transport path, during the transport of just one parin the same direction as screw blades, , with Cartesian
ticle, with an intention to use a screw conveyor as
transporter, but also as the continous pre-mixer.
coordinate changes over time t
The particle path is being extended by addition of
Journal on Processing and Energy in Agriculture 18 (2014) 3
113
Jovanović, Aca et al. / Utilization of Screw Conveyor as Pre-Mixer:Discrete Element Model
complementary helices oriented in the same direction as screw
blades (particle path is enlarged more then three times), or in the
opposite direction of screw blades (when particle path is endured
extended more then four times). The longest path result obtained
in DEM simulation was with the screw conveyor with additional
straight line blade, which is a less more than five times
compared with single flight screw conveyor.
AKNOWLEDGEMENT:The authors wish to express their
gratitude to the Ministry of Education and Science of the Republic of Serbia for the financial support, TR-31055, 2011-2014.
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feeders, Proc. Partec 2001, Int. Congress for Particle
Technology, Nuremberg, Germany, March, 27–29, Paper 69.
Yu, Y., Arnold, P.C. (1997). Theoretical modelling of torque
requirements for single screw feeders, Powder Technol. 93,
151–162.
Roberts, A.W. (1999). The influence of granular vortex motion
on the volumetric performance of enclosed screw conveyors,
Powder Technol. 104, 56–67.
Shimizu, Y., Cundall, P.A. (2001). Three-dimensional DEM
simulation of bulk handling screw conveyors, J. Eng.
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Owen, P.J., Cleary, P.W., McBride, B. (2003). Simulated
granular flow in screw feeders using 3D Discrete Element
Method (DEM), CHEMECA 2003, 31st Australian Chemical
Engineering Conference, 2003, ISBN: 0-86396-829-5, Paper
No. 203.
Cleary, P.W. (2004). Large scale industrial DEM modelling,
Eng. Computation 21, 169–204.
Cleary, P.W. (2007). DEM modelling of particulate flow in a
screw feeder, Progress in Computational Fluid Dynamics 7
(Nos. 2/3/4), 128–138.
Cleary, P.W. (1998). Predicting charge motion, power draw,
segregation, wear and particle breakage in ball mills using
discrete element methods”, Miner. Eng. 11, 1061–1080.
Cleary, P.W. (1998). Discrete Element Modelling of industrial
granular flow applications”, TASK, Quarterly — Scientific
Bulletin 2, 385–416.
Roberts, A.W., Willis, A.H. (1997). Performance of grain
augers, Proceedings of the Institution of Mechanical Engineers
176 (8) (1962) 165–194.
Cleary, P.W., Metcalfe, G., Liffman, K. How well do discrete
element granular flow models capture the essentials of mixing
process?, Inter Conf on CFD in Mineral and Metal Processing
and Power Generation, CSIRO, 149-156.
Received: 28. 02. 2014.
Accepted: 26. 03. 2014.
Journal on Processing and Energy in Agriculture 18 (2014) 3
Biblid: 1821-4487 (2014) 18; 3; p 115-118
UDK: 542.934.8:641.12:582.661.15
Original Scientific Paper
Originalni naučni rad
PHYSICOCHEMICAL CHARACTERICS OF SUGAR BEET MOLASSES USED
AS THE MEDIUM FOR OSMOTIC DEHYDRATION OF PORK MEAT
FIZIČKOHEMIJSKE KARAKTERISTIKE MELASE ŠEĆERNE REPE
KORIŠĆENE KAO MEDIJUM ZA OSMOTSKU DEHIDRACIJU
SVINJSKOG MESA
Mirjana PAVLOVIĆ*, Sanja OSTOJIĆ*, Snežana ZLATANOVIĆ*, Dragana MITIĆ-ĆULAFIĆ**,
Olgica KOVAČEVIĆ*, Darko MICIĆ*
*
University of Belgrade, Institute of General and Physical Chemistry,
Studentski Trg 12, 11000 Belgrade, Serbia
**
University of Belgrade, Faculty of Biology, Studentski Trg 16, 11000, Belgrade, Serbia
e-mail: [email protected]
ABSTRACT
Physicochemical properties of the sugar beet molasses (SBM), used as the medium for osmotic dehydration (OD) of pork meat,
were determined to improve OD process performances. Macroelements content (Na, K, Ca and Mg) decreased in molasses after OD
meat treatment, although rather slightly. Differential scanning calorimetry and modulated differential scanning calorimetry revealed
that there was a strict dependence between water content and temperature of molasses glass transition, and suggested the character
of the thermal process. Influence of the high organic content of molasses on the secondary lipid oxidation products of OD meat were
determined using thiobarbituric acid method.
Key words: molasses, osmotic dehydration, macroelements, lipid oxidation, differential scanning calorimetry.
REZIME
Fizičkohemijske osobine melase šećerne repe, korišćene kao medijum za osmotsku dehidraciju (OD), svinjskog mesa, su bile
praćene da bi se popravile karakteristike OD procesa. Sadržaj makroelemenata (Na, K, Ca and Mg) u melasi opada posle OD tretmana mesa, iako dosta slabo. Diferencijalna skanirajuća kalorimetrija i modulirana diferencijalna skanirajuća kalorimetrija su pokazale da postoji stroga zavisnost između sadržaja vode i temperature staklastog prelaza u melasi, i ukazale na karakter termalnog
procesa. Uticaj visokog sadržaja organskih materija u melasi na sekundarne oksidativne proizvode lipida u mesu je bio praćen
korišćenjem metoda tiobarbituratne kiseline.
Ključne reči: melasa, osmotska dehidratacija, makroelementi, oksidacija lipida, diferencijalana skenirajuca kalorimetrija.
INTRODUCTION
Osmotic dehydration (OD) is one of the most challenging
operations in food dehydration, based on partial removal of water from the food material by direct contact of the product with a
hypertonic solution of salts, sugars, acids, etc., (Raoult-Wack,
1994). Sugar beet molasses (SBM), a byproduct of sugar manufacture, is used as the medium for osmotic dehydration (OD),
primarily due to the high dry matter (65-80%) and specific nutrient content (Luczyñska et al., 2009). Sugars, plant pigments
and organic compounds formed during sugar processing, as well
as minerals and vitamins from SBM penetrate into the food material. Reduction in moisture and enhancement of macro element
content (Luczyñska et al., 2009; Filipčev et al., 2010; Della Rosa
et al., 2001) in the food matrix are among main parameters followed in osmotic dehydration and quality of analytical techniques is crucial for of improvement of OD process performances. SBM is a very specific material and the selection of the
appropriate mineral extraction procedure (Zlatanovic et al,
2012), precise enough for determining the changes of mineral
content of SBM, during osmotic dehydration of pork meat, was
implemented. As water activity (aw) alone was proved to be inadequate in some cases, the concept of glass transition was used
in last two decades as a parameter for quantifying water mobility
and food stability (Oliveira et al., 1999). In this work, thermal
characteristics, by the means of differential scanning calorimetry
(DSC) and modulated differential scanning calorimetry
(MDSC), of molasses, used for osmotic dehydration, has been
studied in the aim of better understanding of molasses’ glass
Journal on Processing and Energy in Agriculture 18 (2014) 3
transition phenomenon. Reduction in moisture and aw and increase of salts concentration lead to the reduction in microbial
growth and differences in lipid oxidation status (Singhal et al.,
1997). The thiobarbituric acid (TBA) test is widely used to evaluate secondary lipid oxidation products in meat. Malondialdehyde (MDA), a secondary oxidation product of polyunsaturated
fatty acids (PUFA) with three or more double bonds, reacts with
TBA to form a stable pink chromophore with maximal absorbance at 532 nm (TBARS532). Certain compounds interfere
with the reaction between TBA and MDA: sugars, water-soluble
proteins and peptides, DNA, volatile aldehydes different to
MDA, pigments, amino acids, nitrites, metals and compounds
with similar spectral properties to that of the TBA–MDA adduct.
Numerous method modifications were developed to reduce these
interfering reactions (Fernandez et al., 1997; Wang et al., 2002).
High level of sucrose (44-54%), other sugars and their degradation products in molasses, used in osmotic dehydration of meat,
could generate interfering yellow chromogen (at 450-460 nm)
overlapping the pink peak (at 530-537 nm) of TBA-MDA adduct. The yellow chromogen is formed by a variety of aldehydic
compounds reacting with TBA (Fernandez et al., 1997). In this
work characterization of SBM, considering mineral content,
thermal analysis and oxidation capacity, i.e. the interferences in
the TBA method, caused by the sugar beet molasses used as solution for osmotic dehydration of pork meat, were studied.
MATERIAL AND METHOD
Experimental setup: Preparation of osmotically dehydrated
pork meat in sugar beet molasses (SBM) has been described in
115
Pavlović, Mirjana et al. / Physicochemical Charact. of Sugar Beet Molasses Used as the Medium for Osmo. Dehyd. of Pork Meat
detail in (Pavlović et al., 2012). Briefly, fresh pork (Musculus pork meat in molasses resulted in the enrichment of meat with
brachii) of normal pH (6.05), was cut into approximately 1x1x1 minerals and the reduction of mineral content of SBM. Contents
cm (1cm3) cubes and osmotically dehydrated in solutions of sug- of macroelements: Na, K, Ca and Mg in SBM before and after
ar beet molasses (81,95 °Brix) at 22°C for 5 hours. Solution to osmotic dehydration, are shown in Table 1.
sample ratio was 10:1 to avoid significant
Table 1. The content of macro elements in sugar beet molasses (SBM), determined by
dilution of the medium by water removal,
which would lead to the local reduction ICP-OES. Results represent mean value ± standard deviation.
Dry matter at Moisture at
of the osmotic driving force during
Na
K
Ca
Mg
Sample
105 oC
105 oC
process. SBM samples before and after
(mg/100 g) (mg/100 g) (mg/100 g) (mg/100 g)
(%)
(%)
osmotic treatment were analyzed.
1. SBM
Physicochemical analysis: Dry mat79.2±0.6
20.7±0.6
749±21
1939±9
289±3
38±1
ter and water content of meat and SBM before OD
2. SBM
samples was determined at 105 °C in a
73.2±0.8
26.8±0.8
689±7
1731±12
268±6
36±1
after OD
laboratory oven until constant weight was
achieved, according to the ISO 1442:1997. The combination of
SBM is a very specific material and the selection of the apthermal treatment at 350 °C, and wet acidic treatment at 160 °C propriate mineral extraction procedure is not an easy task. Difwas used for samples preparation for determination of mineral ferences in sample preparation, selection and implementation of
content. The dry samples were processed for minerals determi- the procedure as well as inhomogeneity of the samples were recnation by wet digestion, where ca. 5 g each, were weighed exact- ognized as the main reasons for results variation. The results obly to four decimal places, and transferred to the vessels, into
tained, with relative standard deviations below 5%, enable reliawhich 4.5 ml 65% HNO3 and 10.5 ml 35% HCl were added.
ble observation of changes in the macro elements composition in
The treatments were repeated to obtain the white sediments that
all materials during the OD process. Comparison of macro elewere dissolved in 0.07 M HNO3. The content of metals present
in the corresponding solutions was determined by inductively ments content between SBM (before OD) and after OD, had
coupled plasma optic emission spectrometry (ICP-OES). ICP- shown significantly higher levels of Na, K and Ca in SBM,
OES measurement was performed using Thermo Scientific which was not the case with Mg content. OD pork meat had a
ICAP 6500 Duo ICP (Thermo Fisher Scientific, Cambridge, significant increase in the content of Na, K and Ca cations with
United Kingdom) spectrometer equipped with RACID86 Charge respect to the content obtained for the raw pork. The content of
Injector Device (CID) detector, standard glass concentric nebu- Mg cation in the OD pork meat was slightly raised and reaches a
lizer, quartz torch, and alumina injector. SBM samples have value similar to the SBM (Zlatanović et al., 2012). The content
been studied by differential scanning calorimetry (DSC) in the of macro elements (Na, K and Ca) in SBM before and after OD,
cyclic heat-cool-heat scans, in the temperature range from -90 o C differs slightly, but significantly, despite the large ratio of OD
to 90 oC, heating rate Hr=10 oC/min and cooling rate Cr=5 solution (SBM) to meat samples. Analysis of the mineral content
o
C/min, N2 purge flow of 50 ml/min. MDSC cyclic heat-cool- of materials during the process of osmotic dehydration allows
heat scans were conducted in temperature range from -90 oC to better control of better control of the technological process.
90 oC, with heating rate Hr (rH)=5 oC/min with modulation of 0.8
From the results obtained, it was found that there was a strict
o
C amplitude and 60s period of modulation, under N2 purge flow dependence between water content and molasses glass transition
of 50 ml/min. Moisture was determined by standard method JUS (Tg) temperature what is in agreement with literature data (SoISO 1442: 1997. All scans were performed on the DSC Q1000 pade, 2007). The transition temperatures (midpoint), Tg, ranged
calorimeter, TA Instruments, DE, USA. The Universal Analy- from -54.3oC to -32.1oC, while the change in heat capacity
sisTM software was used to obtain the glass transition parame- (ΔCp) was from 1.1 to 2.4 J/g/ºC (Fig. 1. and Table 2.). Dried
ters (onset, Tonset; midpoint, Tg; final Tend, and the shift in specifmolasses Tg was found to be -33.0 oC, which is in agreement
ic heat capacity ΔCp). TBA test for secondary lipid oxidation
products was determined in OD meat and SBM using aqueous with the results obtained by the Fox model for glass transition
acid extraction TBA method (EM), (Wang et al., 2002). The in- prediction and predicted Tg of the anhydrous molasses (Sopade
cubation conditions in EM for TBA-reactive substances et al., 2007). The samples with the highest moisture showed the
(TBARS) (Fernandez et al., 1997) were: A) boiling tempera- lowest glass transition temperatures, while the highest glass tranture/25 min with 20 mM TBA, B) 40oC/70 min, with 80 mM sition temperatures were obtained from the most dry molasses
TBA, and C) 20 oC/20 h with 20 mM TBA. The steam distilla- samples. Using MDSC, the reversing and nonreversing thermal
tion TBA method (DM) was employed to evaluate the interfe- events in the low temperature region of molasses have been obrences with the spectrophotometric measurement at around 532 tained, suggesting on the existence of only one thermal process.
nm found in EM. TBARS values were calculated by multiplying
Table 2. Glass transition temperature (Tg), heat capacity
the absorbance values at 532 nm by a constant coefficient Kmed.
(ΔCp) and moisture (%) of sugar beet molasses (SBM) and dried
Kmed value was derived from standard curves and known dilutions of MDA standard (1,1,3,3 tetrametoxypropane, TMP), and SBM.
No.
Sample
Tg (oC)
∆ Cp(W/g)
Moisture (%)
expressed as mg MDA/kg of sample.
Statistical analysis: Microsoft Excel software (Microsoft
1. SBM before OD
-40.04
0.1651
17.66
Office 2003) was used for statistical analysis. All measurements
2. SBM 3. after OD
-33.54
0.1374
28.03
were performed in triplicate.
RESULTS AND DISCUSSION
Several samples of sugar beet molasses (SBM), obtained
from three Serbian sugar mills with different water content, were
used for osmotic dehydratation of pork meat. Treatment of the
116
3.
SBM before OD
-42.20
0.1571
20.70
4.
SBM 5. after OD
-38.51
0.1558
26.79
5.
SBM before OD
-47.81
0.1848
20.73
6.
Dried SBM
-32.53
0.0823
0.00
Journal on Processing and Energy in Agriculture 18 (2014) 3
Pavlović, Mirjana et al. / Physicochemical Charact. of Sugar Beet Molasses Used as the Medium for Osmo. Dehyd. of Pork Meat
perature. Hence, the interfering colorings can be
reduced by incubating TBA and MDA at lower
temperatures, while the reaction time can be reduced by increasing of TBA concentrations from
20 mM to 80 mM. The modified method can be
used to measure MDA in the presence of high
concentrations of interfering sucrose (higher than
4%), or other similar interfering agents (Wang et
al., 2002). The method of Wang et al. (TBA method B) could be the appropriate method for
TBARS measurement in pork meat osmotically
dehydrated in SBM which contained 4-13% of sucrose. The difficulty to determine the optimal conditions for the release of MDA from its bound
forms in muscles without using strong acidic conditions and heating, which, could destabilize the
MDA-TBA complex (Fernandez et al., 1997),
was suggestive of combining mild extraction procedure (Wang et al., 2002) with different incubation temperatures and TBA concentrations in EM.
No significant differences in TBARS values were
found in molasses samples before and after OD.
Fig. 1. MDSC curves of sugar beet molasses (SBM) before and after
osmotic dehydration process and of dried SBM. SBM samples 1-6 are
designated as in Table 2
CONCLUSION
Interferences, which cause erroneously high value of TBARS
in meat samples dehydrated in molasses, were detected as abSugar beet molasses (SBM), a byproduct of sugar manufacsorption at 350 nm, 450-460 nm, and 532 nm in SBM itself, us- ture, used as the medium for osmotic dehydration, is a very speing aqueous acid extraction method (EM) under different condi- cific material in terms of the selection of the appropriate metions of incubation (A, B and C) (Pavlović et al., 2012). These thods for monitoring of the OD process. The combination of
spectrophotometric interferences, found in diluted molasses so- thermal treatment at 350 0C, and wet acidic treatment at 160 oC
lutions, are overlapping the pink peak (532 nm), characteristic was found as optimal for the mineral extraction procedure. Confor MDA. The reaction with TBA was dependent on molasses tent of macro-elements (Na, K, Ca and Mg) decreased in moconcentration and was maximal at 100oC, as shown in Fig. 2. lasses after OD meat treatment, although rather weakly. Diffe(scan 2 and 4).
rential scanning calorimetry and modulated differential scanning
2.0
Absorbance
4
TBA method A
1.5
1.0
0.5
3
2
1
5
0.0
400
450
500
550
600
Wavelength (nm)
Fig. 2. Scans of sugar beet molasses and sucrose absorbance in
TBA method A (EM, 100oC/25 min, 20 mM TBA). Scans: 1) 10%
molasses, before TBA reaction; 2) 10% molasses, after TBA
reaction; 3) 20% molasses, before TBA reaction;
4) 20% molasses, after TBA reaction,
5) 10% sucrose after TBA reaction
It was slower when the incubation temperature was
decreased, (data not shown). It is known that sucrose reacts with
TBA, generating a yellow adduct with maximum absorbance at
450 nm (Fig. 2., scan 5), when the incubation temperature is
above 50 °C (Wang et al., 2002). It is evident that some other
TBA-reactive compounds, possibly antioxidants (Guimaraes et
al., 2007), as melanoidin compounds and caramels, may be
present in the sugar molasses, which can lead to interferences
with the spectrophotometric measurement and hence, cause an
overestimation of the results. The reaction between TBA and
MDA is more specific at room temperature than at boiling tem-
Journal on Processing and Energy in Agriculture 18 (2014) 3
calorimetry revealed that there was a strict dependence between
water content and temperature of molasses glass transition.
Samples of highest moisture showed the lowest glass transition
temperatures, while the highest glass transition temperatures
were obtained with the sample of dried molasses. Using MDSC,
the reversing and non reversing thermal events in the low temperature region of molasses have been obtained, suggesting on
one thermal process. The effectiveness of three TBA tests in minimizing the interferences of molasses ingredients was measured
by aqueous acid extraction method (EM) under different conditions of incubation. TBA-EM at high incubation temperature
(100oC) may be an inadequate method for the analysis of oxidative deterioration of meat samples dehydrated in molasses, due
to interferences which cause erroneously high values of TBA,
detected as absorption at 350 nm and 450-460 nm, which are
overlapping the pink peak (max. 532 nm), characteristic for
MDA. TBA-EM procedure at low incubation temperature (40oC)
and elevated TBA concentration (80 mM) was the most sensitive
of the studied TBA methods.
ACKNOWLEDGEMENTS:This work was supported by the
Ministry of Education, Science and Technological Development
of the Republic of Serbia, under the Project No TR-31055 and
TR-31093.
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Zlatanović, S., Kovaćević, O. A., Ostojić,S., Dojčinović, B. P.,
Pavlović, M., Šuput. D. (2012). Macro elements composition
of the osmotically dehydrated pork meat in sugar beet molasses
solution, Proceedings of the 11th internationalconference of
fundamental and applied aspects of physical chemistry PHYSICAL CHEMISTRY 2012, September 24-28, Belgrade,
Serbia, 2, 766-768.
Received: 03. 03. 2014.
Accepted: 28. 03. 2014.
Journal on Processing and Energy in Agriculture 18 (2014) 3
Biblid: 1821-4487 (2014) 18; 3; p 119-122
UDK: 582.661.15
Original Scientific Paper
Originalni naučni rad
THE EFFECT OF CALCIUM SULPHATE, ALUMINIUM SULPHATE
AND POLYELECTROLYTE ON SEPARATION OF PECTIN
FROM THE SUGAR BEET JUICE
UTICAJ KALCIJUM SULFATA, ALUMINIJUM SULFATA I
POLIELEKTROLITA NA IZDVAJANJE
PEKTINA SOKA ŠEĆERNE REPE
Tatjana KULJANIN*, Biljana LONČAR*, Milica NIĆETIN*, Vladimir FILIPOVIĆ*, Violeta KNEŽEVIĆ*, Jasna GRBIĆ**
*
University of Novi Sad, Faculty of Technology, Bulevar Cara Lazara 1, 21000 Novi Sad, Serbia
**
University of Novi Sad, Institute for Food Technology, Bulevar Cara Lazara 1,
21000 Novi Sad, Serbia
e-mail: [email protected]
ABSTRACT
In the sugar industry, calcium ions (in the form of CaO) that are commonly used to eliminate the pectin from beet juice have a
relatively low binding affinity. The quantities of used lime are very large (15 g/100 g juice). The precipitation of pectin could be
achieved by the charge neutralization. Compounds with bi- and trivalent cations such as CaSO4 and Al2(SO4)3 could be used to extract pectin from colloidal systems. Application of polyelectrolyte previously referred to the improvement of flocculation in water
treatment and sugar cane juice.Model - pectin solutions (50 cm3 and 0.1 % wt.) were treated with different concentration of CaSO4
and Al2(SO4). Optimal amounts of applied coagulants, determined using measurements of zeta potential were: 410 mg/dm 3 for CaSO4
and 110 mg/dm3 for Al2(SO4)3.By adding a cationic polyelectrolyte (1, 3 and 5 mg/dm3), the most efficient separation of pectin was
achieved with polyelectrolyte concentration 3 mg/dm3. Adding this type polyelectrolyte, amounts of applied coagulants required for
charge neutralization (zero zeta potential) were reduced. These amounts were 460 mg CaSO4 and 128 mg Al2( SO4)3/g pectin and significantly less than the amount of CaO used in the conventional process of sugar beet juice clarification (9 g/g pectin).
Key words: calcium and aluminium sulphate, pectin, sugar beet, zeta potential.
REZIME
U industriji šećera, kalcijumovi joni (u vidu CaO) koji se najčešće koriste za ukljanjanje pektina iz soka šećerne repe imaju relativno mali afinitet vezivanja. Količine kreča upotrebljene u tu svrhu su vrlo velike (oko 15 g CaO/100 g soka). Taloženje pektina moglo
bi se izvoditi procesom razelektrisanja pektinskih čestica hemiskim putem. Naime, jedinjenja sa dvo- i trovalentnim katjonima kao što
su CaSO4 i Al2(SO4)3 mogla bi se upotebiti za izdvajanje pektina iz koloidnih sistema. Aluminijum sulfat se najčešće koristi u obradi
otpadnih voda dok se primena polielektrolita (katjonskih i anjonskih) dosad odnosila na poboljšanje flokulacije u obradi otpadnih
voda i soka šećerne trske.Model-rastvori pektina (zapremine 50 cm3 i koncentracije 0,1 % mas.) tretirani su sa 7 različitih
koncentracija rastvora CaSO4 i Al2(SO4)3. Optimalne količine primenjenih koagulanata, određivane metodom merenja Zeta
potencijala iznosile su: 410 mg/dm3 rastvora (CaSO4) i 110 mg/dm3 rastvora (Al2(SO4)3 .Dodavanjem katjonskog polielektrolita
(MAGNAFLOC LT-24, koncentracije 1, 3 i 5 mg/dm3) u pektinske rastvore, najveća efikasnost izdvajanja pektina postignuta je sa
koncentracijom polielektrolita 3 mg/dm3. Dodavanjem ovog tipa polielektrolita, smanjile su se optimalne količine primenjenih
koagulanata neophodnih za razelektrisanje pektinskih čestica (nulti Zeta potencijal). Ove količine su iznosile 460 mg/gpektina (CaSO4) i
128 mg/gpektina (Al2(SO4)3) i značajno su manje od prosečne količine CaO koji se upotrebljava u klasičnom procesu čišćenja soka
šećerne repe (oko 9 g/gpektina).
Ključne reči: kalcijum i aluminijum sulfat, pektini, šećerna repa, zeta potencijal
INTRODUCTION
Separation of non-sucrose compounds, above all pectin, from
sugar beet juice is mostly done by CaO in form of Ca(OH)2.
However, in sugar industry, great amounts of this compound are
needed, but this can have a negative consequence on surrounding
soil and lead to its alkalization (Haapala et al., 1996). It is well
known that pectin, proteins and other colloidal particles in
solution like sugar beet juice are negatively charged which
prevents their coagulation and precipitation. Addition of
oppositely charged ions with higher valence would lead to
neutralization of these macromolecules. In this way stabilization
of the system would be disturbed and conditions for coagulation
and precipitation would occur (Lević et al., 2007; Schneider et
al., 2011, Kuljanin et al., 2013). The most efficient method for
Journal on Processing and Energy in Agriculture 18 (2014) 3
monitoring the process of colloidal particles neutralization is
zeta potential measurement. It is know that every particle in
colloidal solution is surrounded with double electrical layer
consisting of static and diffusion layer. Zeta or electrokinetical
potential is easily measurable size and represents the difference
between the potential of diffusion and stationary layer (Koper,
2007; Kuljanin et al., 2010, Kuljanin et al., 2013).
Addition of Ca2+ ions leads to charge neutralization when
electrostatic interactions occur between these ions and
negatively charged side chains of polysaccharides in pectins.
Presence of Ca2+ ions, in hydrophilic macromolecules (such as
pectin and proteins) causes significant decrease of hydration
which is, in addition to the charge neutralization, a precondition
for more rapid coagulation and precipitation of these
macromolecules (Garnier et al., 1994). In the article of Kuljanin
119
Kuljanin, Tatjana et al./The Effect of Ca-Sulphate, Al-Sulphate and Polyelectrolyte on separation of Pectin from the Sugar Beet Juice
et al. 2014, the effect of calcium compounds, CaSO4 and
Ca(OH)2 under the same experimental conditions was studied. It
was found that Ca2+ ions attached to SO4- anions show higher
binding affinity for the polysaccharide pectin than Ca2+ ions
associated with (OH)1- anions which are used in the traditional
processing of sugar beet juice. In a previous paper (Lević et al.,
2007), negligible differences were reported in the strength of
CaSO4 and CaCl2 binding with pectin macromolecules.
Aluminium salts, in the form of hydrolysed salt Al2(SO4)3,
are commonly used for purification of fresh and waste water
(Duan and Gregory, 2003; Duan et, al., 2002). Lipets and Oleinik in 1972 in Russia examined aluminum sulfate and aluminum
chloride as sugar beet extract clarificants. They reported on the
use of aluminum salts in sucrose extraction and juice clarification in the sugar factory extensively.
By studying the bonding strength of various metal ions with
humic materials in water, it was found that Al3+ ions are 6 – 7
times more efficient than Ca2+ ions (Kinniburgh et al., 1999).
Al2(SO4)3 was also proved to be effective in the chemical
processing of molasses (Lević et al., 2005). In this paper,
optimal amounts of Al2(SO4)3 were determined by zeta potential
measurement method.
Coagulation
and
precipitation
of
undesirable
macromolecules (such as pectin of sugar beet juice) can be
improved by using high molecular weight polyelectrolyte. They
act by inter-particle bridging mechanism when the particles are
adsorbed within the polymer chains of polyelectrolyte (Kuljanin
et al., 2012a; Hilal et al., 2008; Pattabi et al., 2000).
Polyelectrolyte (cationic and anionic), are commonly used for
purification of waste water (Baraniak & Walerianczyk, 2003,
Pattabi et al., 2000) as well as for improvement of the
flocculation in sugar cane juice processing (Doherty et al., 2003;
Gorjian et al., 2001). In previous work (Kuljanin et al., 2012.a;
Kuljanin et al., 2012.b), it was found that separation of the
protein and pectin of sugar beet juice is more efficient, when the
cationic polyelectrolyte is used in combination with Al2(SO4)3
and CuSO4.
The aim of this study was to compare effects of CaSO4 with
Al2(SO4)3 in combination with cationic polyelectrolyte, on the
efficiency of pectin extraction from sugar beet juice. The
measurements were performed using electrophoretic method
(measurement of zeta potential) which showed an advantage
over the method of measuring the residual turbidity of the
solution (Kuljanin et al., 2013).
MATERIAL AND METHOD
Pectin preparation was extracted from the pressed sugar beet
cuttings obtained in industrial processing of sugar beet (sugar
factory from Žabalj, Serbia). The dry matter content of the
pressed sugar beet cuttings was 20 % (mass). For pectin
extraction calcium and aluminium sulphate were used in a
crystal- hydrated form (CaSO4 x 7H2O and Al2(SO4)3 x 18H2O)
in the form of aqueous solutions, (manufacturer's ''Zorka
Pharma'', Šabac, Serbia). To correct the pH value in presence of
Al2(SO4)3, an equivalent amount of Na2CO3 was used. In
addition to these coagulants, the cationic polyelectrolyte
(MAGNAFLOC LT-24) high-purity (99%), production of "Low
Moor," Bradford, England was also used.
Pectin preparation was isolated by extraction in acidic
condition by standard laboratory procedure AOAC (2000).
Previously, multiple washing of fresh-prepared sugar beet
cuttings with distilled water slightly acidified with HCl (pH 5.5)
120
was done. Thereafter, extraction was carried out discontinuously
by aqueous HCl solution in the extractor with volume of 2 dm3.
The mass ratio of sugar beet cuttings to solvent was 1:10.
Extraction was performed at pH 3.5 and 85°C during 2.5 h. High
molecular colloidal fraction was isolated from extract by
multistage precipitation with 70% ethanol solution. The
precipitated colloids were left over night to deposit and obtained
sediment was washed out with 70% ethanol solution. Pectin
preparation, at the end was dried in a vacuum drier for 12 hours
at 70 °C. Procedure was repeated several times and basic
parameters of pectin preparation were determined according to
standard methods of AOAC (2000).
The degree of esterification of pectin preparation was
calculated over the equivalents of free (X) and the esterified
carboxyl groups (Y), using equation:
DE 
Y
100
XY
(1)
Mean molar mass of the protein and the pectin preparation
was determined using spectrophotometry and the refractometer,
by the method Kar-a i Arslan-a (Kuljanin et al., 2010).
The experiment has tested the model-solutions of pectin
preparations concentrations of 0.1 % (mass). Working solutions
were prepared by dissolving 1 g of pectin preparation in 250 cm3
of distilled water and left over night to swallow. After that,
distilled water was added up to 1 dm3, and for every
measurement 50 cm3 was separated. After dissolution of 1 g
Al2(SO4)3 and CaSO4 in 200 cm3 of distilled water, an
appropriate amount was collected by pipette and added to 50
cm3 of pectin solution (0.1 mass. %). The obtained
concentrations of CaSO4 were in the range of 50 to 450 mg/dm3
while concentrations of Al2(SO4)3, were in range 50 – 200
mg/dm3 (figure1 and 2). All measurements were performed at
pH = 7. At this pH, Al3+ and Ca2+ ions have limited solubility
and hidrolized cationic forms are dominate (Duan and Gregory,
2003; Duan et, al., 2002). To obtained desired solution alcality
(pH=7), Na2CO3 was added to Al2(SO4)3 (mass ratio of Na2CO3
to Al2(SO4)3 was 1:1.07, calculated on pure Al2(SO4)3) (Kuljanin
et al., 2012.b).
After the coagulants CaSO4 and Al2(SO4)3 were added to the
tested preparation, pH was adjusted and the solution was stirred
for 30 min on a high-speed magnetic stirrer, (stirring speed 500
o/min). After aging the solution for 5 min, zeta potential of clear
part of the solution was measured. The measurements were
performed at room temperature.
In the second phase of the experiment, in addition to
coagulation, a
cationic
polyelectrolyte
was
added
(MAGNAFLOC LT-24). The starting solution was prepared by
dissolving 0.5 g of polyelectrolyte in 100 cm3 of distilled water
and left overnight at room temperature to swell. Using this
solution, the concentrations of solutions were prepared: 1, 3 and
5 mg/dm3. These solutions were added to a solution of pectin
preparation as described by Kuljanin et al., 2012.b.
Zeta potential was determined by electrophoretic method
using a commercial apparatus ZETA-METER ZM 77 (Riddick,
1975). On a stereoscopic microscope was read the time for
which solution particle exceeds one standard micrometre
division. An average value of 20 readings was used to derive the
zeta potential of colloidal particles in the tested solutions using a
diagram (based on the Helmoltz-Smoluchowski equation for
electrophoretic mobility of colloidal particles). Results represent
an average value of 3 measurements. Experiments were
performed at 6-fold magnitude on stereoscopic microscope with
Journal on Processing and Energy in Agriculture 18 (2014) 3
Kuljanin, Tatjana et al./The Effect of Ca-Sulphate, Al-Sulphate and Polyelectrolyte on separation of Pectin from the Sugar Beet Juice
voltage adjusted at 150 V. Immediately before zeta potential
measurements, solution temperatures were measured. Zeta potential was read from the diagram and multiplied by correction
factor for given temperature.
and higher ions charge, with smaller amounts lower the zeta potential to zero
20
RESULTS AND DISCUSSION
Table 1. Physical-chemical properties of pectin preparations
Solid Equivalent Equivalent Content of
Degree of
Mean
content of free
of ester. galacturonic esterification molar
SC
COOH
COOH
acid (%)
DE
mass,
(g/100g)
groups,
groups
MWsr
X · 105
Y · 105
(kg/kmol)
80.35
24.58
16.05
72.24
39.50
87 720
The content of galacturonic acid (degree of purity) and the
degree of esterification in the test preparation corresponds to the
mean value of the pectin contents and the degree of esterification
in sugar beet raw juice. The obtained preparation belongs to the
group of less esterified pectin (DE < 50). This means a greater
ability to bind cations to macromolecules of sugar beet juice, due
to the greater presence of the free carboxyl groups (COO-). More
favourable for removal process are pectins with low degree of
esterification (< 25 %) since they include a number of free functional groups in its structure. Also advantageous for the removal
are pectins with larger molar mass as in the presence of the
cation, there is greater possibility for crosslinking chains in galacturonic acid.
Influence of CaSO4 amount to change the zeta potential of
pectin preparations solution without the addition of polyelectrolyte and with a cationic polyelectrolyte at 1, 3 and 5 mg/dm3
concentration, is shown in Figure 1. Influence of Al2(SO4)3 to
change the zeta potential of pectin solution using the same type
of polyelectrolyte (concentrations 1, 3 and 5 mg/dm3), was studied in previous works (Kuljanin et al., 2012.a; Kuljanin et al.,
2012.b) and it is shown in Figure 2.
10
Zeta potential (mV)
5
0
-5
50
100
150
200
250
300
350
400
450
-10
-15
-20
-25
Concentration of Ca-sulphate (mg/dm3)
Pectin solution without electrolyte
Pectin solution with 1 mg/dm3 polyelectrolyte
Pectin solution with 3 mg/dm3 polyelectrolyte
Pectin solution with 5 mg/dm3 polyelectrolyte
Fig. 1. Influence of CaSO4 on change in the zeta potential pectin
solution without the addition of polyelectrolyte and cationic
polyelectrolyte concentration of 1, 3 and 5 mg/dm3
Substitution of zeta potential sign from "-" to "+" in the
range of tested concentrations of CaSO4 and Al2(SO4)3 showed
that the total charge carried by Ca+2, and Al+3 ions (as well as H+
ions from the solution) became greater by absolute value of the
negative charge on the surface of the macromolecule. According
to Schulce-Hardy-s rule, Al+3 ions, due to the higher valence,
Journal on Processing and Energy in Agriculture 18 (2014) 3
0
50
75
100
125
150
175
200
-10
-20
-30
Concentration of Al-sulphate (mg/dm3)
Pectin solution without polielectrolyte
Pectin solution with 1 mg/dm3 polyelectrolyte
Pectin solution with 3 mg/dm3 polyelectrolyte
Pectin solution with 5 mg/dm3 polyelectrolyte
Fig. 2. Influence of Al2(SO4)3 amount on the change in zeta
potential pectin solution without polyelectrolyte and with the
addition of cationic polyelectrolyte concentration 1, 3 and 5
mg/dm3 (Kuljanin et al., 2012.a)
450
Optimal concentration of Ca /
Al sulphate (mg/dm3)
Results of measuring pectin preparations composition are
given in table 1.
Zeta potential (mV)
10
Ca-sulphate
Al-sulphate
400
350
300
250
200
150
100
50
0
1
2
3
4
1 – pectin solution without polyelectrolyte
2 - pectin solution with 1 mg/dm3 polyelectrolyte
3 - pectin solution with 3 mg/dm3 polyelectrolyte
4 - pectin solution with 5 mg/dm3 polyelectrolyte
Fig. 3. Optimal concentrations of Ca and Al-sulphate to achieve
zero zeta potential values of pectin solution without and with the
addition of polyelectrolyte
The higher affinity of Al3+ ions to sugar beet pectin can be
explained by hydrolysis of Al2 (SO4)3 when products of hydrolysis of a large positive charge are created. They are binding to the
COO- groups of pectin macromolecules forming surface complexes. The amounts of Ca2+ ions originating from CaSO4 were
compared with the amounts of Al3+ ions from Al2(SO4)3 to
achieve zero zeta potential values. It takes about 3.5 times as
much of Ca2+ ions in comparison with Al3+ ions for zeta potential to reach zero value (410 mg/dm3 CaSO4 and 110 mg/dm3
Al2(SO4)3). This is explained by the smaller electric charge of
these ions and the last place that is on a scale binding affinity of
divalent ions, is occupied by Ca2+ ions (Kuljanin et al., 2010;
Kuljanin et al., 2012.b). This means that Ca2+ ions with COOgroups of pectin macromolecules bind only with weak electrostatic forces.
By adding a cationic polyelectrolyte (MAGNAFLOC LT-24)
at 1 mg/dm3, zeta potential changes are negligible. By adding a
cationic polyelectrolyte at 3 and 5 mg/dm3, the required amount
of CaSO4 and Al2(SO4)3 for achieving zero zeta potential value,
were reduced in the interval of 15 up to 130 mg/dm3. Concentrations of polyelectrolyte at 3 and 5 mg/dm3, showed a similar effect on the change of zeta potential (Figure 3). Using polyelec-
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Kuljanin, Tatjana et al./The Effect of Ca-Sulphate, Al-Sulphate and Polyelectrolyte on separation of Pectin from the Sugar Beet Juice
trolyte concentration at 3 mg/dm3, the required amount of coagulant CaSO4 for achieving zero zeta potential value is 280 mg/dm3
(460 mg/gpectin), while for Al2(SO4)3, that amount is 95 mg/dm3
(128 mg/gpectin) (Figures 1 and 2). Based on this, it can be concluded that cationic polyelectrolytes probably besides interparticle bridging mechanism, provide additional charge neutralization. This means that the cationic polyelectrolytes have a function of coagulant (via charge neutralization) and flocculants (via
inter-particle bridging).
The amounts of both examined coagulants were substantially
less than the average amount of CaO used in the conventional
process of sugar beet juice clarification (about 9 g/gpectin).
It is known that aluminum salts may have unfavorable effect
in the nutrition. For example, in 1965, animal experiments suggested a possible connection between aluminium and Alzheimer’s disease. Analysis of aluminium content of a number of
foods and food products was undertaken in order to evaluate the
nutritional intake of aluminium (Stahl et, al., 2011). FAO/WHO
Expert Committee on Food Additives reduced the provisional
tolerable weekly intake value for aluminium from 7 mg/kg body
weight/week to 1 mg/ kg body weight/week.
For this reason, CaSO4 is recommended as a partial or total
replacement for the traditional coagulant in the process of sugar
beet juice clarification. By adequate dosing of CaSO4 and cationic polyelectrolyte as well as controlling zeta potential, greater
efficiency of pectin separation in the phase of clarification of
sugar beet juice would be achieved.
CONCLUSION
The amounts of CaSO4 were compared with the amounts of
Al2(SO4)3 in combination with a cationic polyelectrolyte to
achieve zero zeta potential values when creating the optimal
conditions for extracting pectin from solution. Al3+ ions possess
a greater bonding strength with sugar beet pectin compared to
Ca2+ ions. However, CaSO4 would be more suitable for any industrial application because of acceptable prices and favourable
solubility in water. In the presence of cationic polyelectrolyte
(MAGNAFLOC LT-24) concentrations of 3 mg/dm3, CaSO4
showed the highest efficiency for pectin extraction from solution. Cationic polyelectrolyte, in this case, has a dual functioncoagulant (via charge neutralization mechanism) and flocculants
(via inter-particle bridging mechanism).
The quantity of CaSO4 using cationic polyelectrolyte are up
to 25 times smaller than the average amount of traditional coagulant CaO which is commonly used in the process of sugar beet
juice clarification.
ACKNOWLEDGMENT: This research is part of the project
supported by the Ministry of Education, Science and Technological Development of the Republic of Serbia, Project
III 46005.
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Received: 04. 03. 2014.
Accepted: 25. 03. 2014.
Journal on Processing and Energy in Agriculture 18 (2014) 3
Biblid: 1821-4487 (2014) 18; 3; p 123-125
UDK: 531.3:582.635.5
Original Scientific Paper
Originalni naučni rad
OSMOTIC TREATMENT OF NETTLE LEAVES IN TWO
DIFERENT SOLUTIONS- MASS TRANSFER KINETICS
OSMOTSKI TRETMAN LISTA KOPRIVE U DVA RAZLIČITA
RASTVORA-KINETIKA PRENOSA MASE
Violeta KNEŽEVIĆ*, Biljana LONČAR*, Milica NIĆETIN*, Vladimir FILIPOVIĆ*,
Lato PEZO**, Tatjana KULJANIN*, Ljubinko LEVIĆ*
*
University of Novi Sad, Faculty of Technology, Bulevar Cara Lazara 1,
21000 Novi Sad, Serbia
**
University of Beograd, Institute of General and Physical Chemistry,
Studentski trg 12/V11000 Beograd, Serbia
e-mail:[email protected]
ABSTRACT
The presented paper describes an investigation of osmotic treatment of nettle leaves in two different osmotic solutions (sugar beet
molasses and ternary solution), under atmospheric pressure, at room temperature. The main objective was to examine the influence
of type of osmotic agents and immersion time on the mass transfer phenomena during osmotic treatment. Different kinetics parameters were monitored (water loss, solid gain, water loss to solid gain ratio, weight reduction, normalized solid content and normalized
moisture content), after 30-90 min of process. Principal Component Analysis showed good discrimination capabilities for different
samples, while Standard Score was used in optimal process parameters determination.
Key words: osmotic dehydration, nettle leaf, mass transfer kinetics.
REZIME
Ovaj rad predstavlja istraživanje osmotskog tretmana lista koprive u dva različita osmotska rastvora (melasa i ternari rastvor) na
sobnoj temperaturi i atmosferskom pritisku. Glavni cilj je bio da se ispita uticaj vrste osmotskog rastvora i vremena imerzije na fenomene prenosa mase tokom osmotskog tretmana. Praćeni su različiti parametri kinetike (gubitak vode, priraštaj suve materije, odnos gubitka vode i priraštaja suve materije, normalni sadržaj suve materije i normalni sadržaj vlage) nakon 30-90 minuta proceasa.
PCA je pokazala dobre mogućnosti za razdvajanje grupa različitih uzoraka, u odnosu na određivane kinetičke parametre, a SS je
korišćena za određivanje optimalnih procesnih parametara.
Ključne reči: osmotska dehidratacija, list koprive, kinetika prenosa mase.
INTRODUCTION
The stinging nettle designated as a detestable weed plant,
spread almost all over the world is a treasure of active components. Due to the fact that stinging nettle leaves are rich in flavonoids, chlorophylls carotenoids and their degradation products,
vitamins (Rafajlovska et al., 2002; Fiamegos, 2012; Taylor,
2009) proteins (El Haouari et al., 2006), mineral materials, organic acids, oil and other components, the stinging nettle is of
high value in the folk medicine as well as in scientific medicine
(Kukrić et al., 2012; Stanojević et al., 2013).
Osmotic treatment (OT) is an environmentally acceptable,
material gentle drying method, which received considerable attention, due to the low processing temperature,low waste material and low energy requirement (Filipović et al. 2012). OT is used
as a pretreatment for many processes, to improve nutritional,
sensorial and functional properties of food without changing its
integrity (Mišljenović et al. 2012).
OT is a water removal process, based on soaking food (fruit,
vegetable, meat and fish) in a hypertonic solution. In comparison
to other drying treatments main advantages of OT process are
that water is removed in liquid form, at mild temperatures and
osmotic solution can be reused (Ćurčić et al., 2012; Mišljenović
et al., 2011).
The specific objective of this study was to examine the influence of immersion time and the type of osmotic solution on the
efficiency of nettle leaves OT process.
Nettle leaves, are treated at three different immersion time,
using two different osmotic solutions. Experimental results have
been subjected to analysis of variance (ANOVA) to show relations between applied assays (Ćurčić et al., 2012). In order to
Journal on Processing and Energy in Agriculture 18 (2014) 3
enable more comprehensive comparison between investigated
samples, standard score (SS) has been introduced (Koprivica et
al., 2013). Principal Component Analysis (PCA) and Cluster
Analysis (CA) have been applied to classify and discriminate
analysed samples (Brlek et al., 2013).
Nomenclature:
CA- Cluster Analysis
DEI- water loss to solid gain ratio
i.s.w.-initial sample weight
NMC- normalized moisture content
NSC- normalized solid content
OT- osmotic treatment
PCA- Principal Component Analysis
SG- solid gain
SS- Standard Score
WL- water loss
WR- weight reduction
MATERIAL AND METHOD
Nettle leaves (Urtica dioica L.) were collected at local area
just before use. Initial moisture content of nettle was 78%. Before the OT, nettle leaves were cut into rectangles, dimension of
nearly 1x1cm. As hypertonic mediums two different solutions
were used. The first one, osmotic solution, sugar beet molasses,
with initial dry mater content of 85.04%, was obtained from the
sugar factory Pećinci. The second osmotic solution, ternary solution, was made from sucrose in quantity of 1200 g/kg distilled
water, NaCl in quantity of 350 g/kg and distilled water. The
sample to solution ratio was 1:20 (w/w). The process was per-
123
Knežević, Violeta et al. / Osmotic Treatment of Nettle Leaves in Two Diferent Solutions - Mass Transfer Kinetics
formed at solution temperature of 20°C, under atmospheric pressure. After 30, 60 and 90 minutes, the samples were taken out to
be lightly washed with water and gently blotted to remove excessive water. The dry material content of samples was determined by drying at 105 ºC in a heat chamber until constant mass
was achieved (Instrumentaria Sutjeska, Croatia). All analytical
measurements were carried out in accordance to AOAC (2000).
In order to describe the mass transfer kinetics of the OT, experimental data, three key process variables are usually obtained:
moisture content, weight variation and change in the soluble
solids content.
From the obtained data, WL, SG, DEI and WR were determined at different time intervals, according to the following expression (Ćurčić et al., 2012):
WL 
SG 
mi zi  m f z f
mi
m f s f  mi si
mi
WL
SG
WR  WL  SG
m z
NMC 
mi zi
ms
NSC 
mi si
(3)
(4)
(5)
RESULTS AND DISCUSSION
Table 1 shows changes in WL, SG and DEI parameters in
the samples during OT. As predicted, the process leads to an increase in WL and SG of all samples regardless of used conditions.
The most intensive increase in WL was observed as the in(2)
crease from initial 0.00 to 0.52 g/g i.s.w. in molasses solution,
after 90 minutes. Table 1 shows that SG increases with immersion time.
Table1. Experimental results(mean±SD) for nettle leaves during osmotic treatment
process


g
 g fresh sample 




g
 g fresh sample 


DEI 
In case of “the lower, the better” criteria, used for SG score
calculation.
Collected data have been subjected to one-way analysis of
variance (ANOVA) for the comparison of means, and significant
differences are calculated according to post-hoc Tukey’s HSD
(“honestly significant differences”) test at p<0.05 significant
level, 95% confidence limit. Furthermore, principal component
analysis (PCA) and Cluster analysis (CA) have been applied
successfully to classify and discriminate the different samples.
All statistical analyses of the obtained results have been performed using StatSoftStatistica 10.0® software.
(1)
Solution No. t
WL
SG
DEI
NSC
NMC
SS
Molasses 1 30 0.38±0.01b 0.12±0.00b 3.12±0.10a 0.04±0.00b 0.72±0.01c 0.75±0.01a
e
(6)
WR
c
a
a
a
0.60
b
0.74
3 90 0.52±0.01f 0.16±0.00a 3.26±0.01a 0.05±0.00a 1.00±0.00b 1.00±0.00c
0.81
2 60 0.48±0.01 0.15±0.00 3.21±0.09 0.05±0.00 0.92±0.02 0.94±0.01
where: mi and mf are the initial and Ternary 4 30 0.34±0.01 0.17±0.00 2.03±0.06 0.08±0.00 0.76±0.01 0.75±0.01 0.27
final weight (g) of the samples, respec- solution 5 60 0.43±0.01c 0.21±0.00d 2.04±0.03b 0.10±0.00d 0.95±0.01a 0.93±0.01b 0.30
tively; zi and zf are the initial and final
6 90 0.45±0.01d 0.22±0.00e 2.00±0.06b 0.11±0.00e 1.00±0.00b 1.00±0.00c 0.29
mass fraction of water (g water/g sample), respectively; si and sf are the initial Polarity
+
/
/
/
/
and final mass fraction of total solids
(g total solids/g sample), respectively.
Values with the same letter are not statistically different at
ANOVA calculation considered, the followed independent
variables: immersion time (X1) - 30, 60 and 90 min; the type of the p<0.05 level (according to post-hocTukey’s HSD test).
The aim of OT is the achievement of lowest possible solid
osmotic solution (X2) - sugar beet molasses (1) and ternary solution of NaCl, sucrose and water (2). The dependent variables uptake, and the most acceptable results were achieved by using
were the responses(results of analytical determinations): WL molasses solution (0.16 g/g i.s.w.), after 90 minutes of osmotic
(Y1) and SG (Y2). Two mathematical models of the following process. To determine optimal condition for the OT water
form were developed to relate two responses (Y) to two process loss/solid gain ratio must be considered. The highest value of
DEI=WL/SG ratio was 3.26, achieved by immersion of nettle
variables (X):
2
2
leaves for 90 minutes in sugar beet molasses.
(1)
Yk  k0  ki Xi  kii Xi2  k12 X1  X2, k=1-2
ANOVA was conducted to determine the optimum OT coni 1
i 1
ditions (considering maximum of measured WL with lower SG).
where: βk0, βki, βkii, βk12 are constant regression coefficients.
Table 2 shows the ANOVA calculation regarding the response
Min-max normalization is one of the most widely used techmodels developed when the experimental data were fitted to a
nique to compare various characteristics of complex samples de- response surface. The response surface used a first order polytermined using multiple assays, where samples are ranked based nomial (FOP) in the form of Eq. (1) in order to predict all the
on the ratio of raw data and extreme values of the measurement dependent variables.
used. Since the units and the scale of the data from various paTable 2. ANOVA table (sum of squares each assay)
rameters are different, the data in each data set should be transdf
WL
SG
formed into normalized scores, according to following equations:
**
Type of solution
1
0.005
0.005*
a

i
max xi  min xi
, i
(2)
i
i
in case of “the higher, the better” criteria, used for WL score
calculation, or,
xi 
max xi  xi
i
max xi  min xi
i
124
b
c
d
a

max xi  xi
xi  1 
a
i
, i
(3)
Immersion time
1
0.016*
0.002*
Error
3
0.002
0.000
0.868
0.946
r
2
Significant at p<0.05 level, **Significant at p<0.10 level,
95% confidence limit, error terms have been found statistically
insignificant.
Journal on Processing and Energy in Agriculture 18 (2014) 3
Knežević, Violeta et al. / Osmotic Treatment of Nettle Leaves in Two Diferent Solutions - Mass Transfer Kinetics
The analysis revealed that the linear terms contributed substantially in all of the cases to generate a significant FOP model.
WL was significantly affected by all process variables, and the
main influential variable seems to be the treatment time (statistically significant at p<0.05 level, 95% confidence level). The
type of solution was also important for WL calculation, statistically significant at p<0.10 level. SG was more influenced by the
type of used solution, statistically significant at p<0.05 level
(more acceptable results were obtained using sugar beet molasses solution). The impact of production time for evaluation of
SG was also observed, statistically significant at p<0.05 level.
All SOP models had insignificant lack of fit tests, which means
that all the models represented the data satisfactorily. The r2 values for WL (0.868) and SG (0.946) were found very satisfactory
and showed the good fitting of the model to experimental results.
Optimization of the OT was performed using Standard Score
Analysis, to ensure rapid processing conditions (with as low as
possible immersion time) yielding an acceptable product properties (with high WL and low SG), and a high throughput capacity.
The optimum OT conditions for nettle leaves, dehydrated in sugar beet molasses solution are obtained at immersion time of 90
minutes, solution concentration and temperature of 80% and
20°C respectively.
The analysis of dissimilarities in WL, SG, WR, DEI, NSC
and NMC between the samples was investigated by means of
PCA. The number of factors retained in the model for proper
classification of collected data, in original matrix into loading
(observed samples) and score (WL, SG, WR, DEI, NSC and
NMC data) matrices were determined by application of Kaiser
and Rice’s rule. This criterion retains only principal components
with Eigen values >1. First two PCs explained 99.82% of the
total variance in the experimental data (Fig.1a). Projection of the
variables on the factorial plane indicates that DEI and SG contributed mostly to the first PC (52.8% and 36.2%, respectively),
while WL contributed more to the second PC (71.1%), Fig. 1b
shows the dendrogram of CA for the tested samples. Single linkage algorithm and Euclidean distances were used as the measure of proximity among the samples. The PCA results harmonize
with the results of CA, as expectedamong the samples. The PCA
results harmonize with the results of CA, as expected.
environmentally reasonable, because it is a side product of sugar
industry.
ACKNOWLEDGEMENT: These results are part of project
supported by the Ministry of Science and Technological Development of the Republic of Serbia, TR-31055, 2011-2014.
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A., Mekhfi H. (2006). Inhibition of Rat Platelet Aggregation
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Stalk, and Leaves of Nettle, The ScientificWorld Journal, 12.
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Koprivica, Gordana, Mišljenović, Nevena, (2012). Mass
transfer and microbiological profile of pork meat dehydrated in
two different osmotic solutions, Hem. Ind. 66 (5) 743–748.
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Danijela, (2013). Optimization of Osmotic Dehydration of
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Mišljenović, Nevena, Koprivica, Gordana, Pezo,
L., Kuljanin, Tatjana, Bodroža Solarov, Marija,
Filipčev, Bojana (2011). Application of Peleg
model to study mass transfer during osmotic
dehydration of apple in sugar beet molasses. Acta
Periodica Technologica 42, 91-100.
Mišljenović, Nevena, Koprivica, Gordana, Pezo,
L., Lević, Lj., Ćurčić, Biljana, Filipović, V.,
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a)
b)
Nićetin, Milica (2012). Optimization of the
osmotic dehydration of carrot cubes in sugar
Fig 1. a) PCA biplot diagram and b) CA dendogram for osmotic
beetmolasses, Therm Sci. 16 1, 43-52.
of nettle leaves in sugar beet molasses and Ternary solution
Rafajlovska, Vesna, Djarmati, Z., Najdenova,
Valentina, Cvetkov, Lj. (2002). Extraction of stinging nettle
CONCLUSION
(Urtica dioica l.) with supercritical carbon dioxide, BAÜ Fen
Due to well known nutrient profile of sugar beet molasses it
Bil. Enst. Dergisi, 4.2.
is expected that the enrichment of nettle in nutrient could occur,
Stanojević, Ljiljana, Zdravković, A., Stanković, M., Cakić, M.,
which penetrate from molasses to leaves tissue. The predicted
Nikolić, Vesna, Ilić, Dušica (2013). Antioksidativna aktivnost
responses for the optimum drying conditions in sugar beet movodeno-etanolnih ekstrakata iz lista koprive (Urtica dioica L.),
lasses solution were: WL in the close vicinity of 0.52 g/g i.s.w
Savremene tehnologije, 2(1), 51-59.
and SG about 0.16 g/g i.s.w (DEI=3.26, SS=0.81). During OT of Taylor, K. (2009). Biological flora of the British Isles: Urtica
nettle leaves, water removing process was most intensive at the
dioica L, Journal of Ecology, 97(6), 1436–1458, 2009.
beginning and after 60 minutes had tendency of stabilization.
The use of sugar beet molasses as osmotic agent is economy and Received: 28. 02. 2014.
Accepted: 29. 03. 2014.
Journal on Processing and Energy in Agriculture 18 (2014) 3
125
Biblid: 1821-4487 (2014) 18; 3; p 126-128
UDK: 582.542.11:552.53
Original Scientific Paper
Originalni naučni rad
EFFECTS OF SALT FORMS AND CONCENTRATIONS ON
THE ALVEOGRAPH PARAMETERS OF WINTER WHEAT
UTICAJ OBLIKA SOLI I KONCENTRACIJE NA REOLOŠKE
OSOBINE OZIME PŠENICE
*
Péter SIPOS*, Zsófia SZIGETI*, Mária BORBÉLY**
University of Debrecen, Faculty of Agricultural and Food Sciences and Environmental Management,
Institute of Food Science, Quality Assurance and Microbiology
**
University of Debrecen, Agricultural Laboratory Centre
138 Böszörményi street, H-4032 Debrecen, Hungary
email: [email protected]
ABSTRACT
The strong connection between sodium intake and high blood pressure draws attention to the salt content of foodstuffs and initiated programs for reduction sodium chloride contents of foods. About 30% of sodium intake consumed by bakery products, therefore
this product group is especially affected. The effects of different salt concentrations and salt forms on the reologic properties of
dough were evaluated to explore whether their effect can be measured by alveograph test. Five concentrations of five inorganic salt
forms were tested on the alveograph P, L, P/L and W values and it was found that both the form and concentration of used salt influence the rheological readings.
Key words: alveograph, sodium chloride, bakery products.
ABSTRACT
Jaka veza između unosa natrijum hlorida i visokog krvnog pritiska skreće pažnju na sadržaj soli u namirnicama i inicira
pokretanje programa za smanjenje sadržaja natrijum hlorida u namirnicama. Oko 30% od ukupnog unosa soli u organizam, unosi se
konzumiranjem pekarskih proizvoda, i to je razlog zbog čega je ova grupa proizvoda posebno uticajna. Dejstva različitih
koncentracija soli i oblika soli na reološka svojstva testa su ocenjivani kako bi se istražilo da li se njihovo dejstvo može meriti
pomoću alveograf testa. Različite koncentracije pet neorganskih soli su testirani na alveograf P, L, P / L i V vrednosti i utvrđeno je
da forma i kontracija soli ima uticaj na reološka merenja.
Ključne reči: alveograf test, natrijum hlorid, pekarski proizvodi.
INTRODUCTION
The bakery products are one of the most common staple
foods and their safety is an important issue of food production.
Their assessments are diversified: their nutritional value is high
because of the energy and protein content, but the products made
from white flour are condemned due their high energy and low
fiber contents and the whole meal products are exposed to the
accusation of presence of contaminants. Their sodium contents
are reasons for negative perceptions of nutrition science and the
reduction of their consumption or the reduction of their salt content is one of the new issues of bakeries.
The sodium is essential element due its role in the osmotic
balance of human body, maintaining the digestion by function in
production of acids of stomach, helping maintaining the pH and
nerve impulse transmission (Reddy et al., 1991; Batmanghelidj,
2008), but the highest emphasis is on its function in blood pressure nowadays. Sodium intake was found as the primary reason
for raised blood pressure (He and MacGregor, 2007; Jones,
2008; Satin, 2008) and the strong connection between blood
pressure and sodium intake is valid both for normal and hypertonic people and decrease in sodium intake results immediately
and linear decrease in blood pressure (Kurtzman, 2001). Six
grams decrease in salt intake should decrease the risk of stroke
by 24% and the risk of coronary diseases by 18% (Strazzullo et
al., 2004).
The most sodium is consumed as sodium chloride (salt). The
nutritionally optimal daily intake is 5 g for adults and 3 g for infants, but an international comparison found that almost all the
countries consumes much more than the recommended: in the
member countries of the European Union the average is 8 to 12
g/day (EU, 2012), but the highest values are found in Hungary;
the national intake is about threefoldfourfold of the recom-
126
mended value for men (about 17 g), twofold-threefold for
women (12 g) and unfortunately it is about 6.9 g/day for kindergarteners (Martos, 2010).
Several projects started to decrease the salt content of foodstuffs worldwide. In New Zealand it was recommended to decrease the sodium intake by 25%, as about only 75% of total sodium content is required for food processing in average (Mhurchu et al., 2003). The Food Standards Agency (FSA) and the UK
Committee on Medical Aspects of Food and Nutrition Policy
(COMA) started an anti-salt campaign in the food industry to
encourage the consumers having no more than 2,3 g sodium a
day, but only a slight decrease was found; the average consumption reduced only from 3.8 to 3.6 g (FSA, 2007). Similarly,
Hungary announced the National Salt-Decreasing Program
(Nemzeti sócsökkentő program), undertaking 16% decrease in
four years (Martos, 2010). In Hungary the allowed sodium chloride content of bread products is 2.8% but it will be decreased to
2.35% to 2018 in this program.
The main source of salt in human diet is food; about 70-75%
of the total intake comes from our foodstuffs. Its taste is required
by customers, have an effect on the technological properties of
food raw materials and it is maybe the first chemical preservative (Hutton, 2002). The bakery and meat products cover about
60% of total intake while the other ones have their contributions
below 10% (Angus, 2007; Lynch et al., 2009). The risk of this
foodstuff is especially significant in Hungary as the cereal mostly bread - consumption is relatively high in our country.
The traditional bread, as basic bakery product contains 2 per
cent salt by the weight of flour (Cauvain and Young, 1998). Its
main role is giving taste for the bread and its lack results tasteless flavour. However, consumer studies prove that the reduction
is possible: 50 to 75% decrease in the case of bakery products do
not noticed by average consumers (Wyatt, 1983; Rogers and
Journal on Processing and Energy in Agriculture 18 (2014) 3
Sipos, Péter et al. / Effects of Salt Forms and Concentrations on the Alveograph Parameters of Winter Wheat
Neal, 1999; Unbehend and Namiljav, 2009) and same experiences were found for other product groups too (Hutton, 2002;
Mitchell et al., 2009).
Salt stabilizes the fermentation processes also during rising
and baking. Dough made without salt is gassy, sour dough and
its bread has poor texture (Matz, 1992). It also have significant
effect on the gluten structure and it is basically caused by the
change in the solubility of proteins, the ionic concentrations and
pH. The gluten network has a strong net positive charge which
results that side-chains repulse each other, and keep the protein
chains from interacting with each other, resulting weaker dough
structure (Preston, 1981). The different salts alter the hydrophobic interactions in the forming dough (Danno and Hoseney,
1982). On the other hands, the chloride and sodium ions also
have effect on the stability of proteins: both the sodium and
chloride ions are nonchaotropic ones, thus have ability for protein stabilization. (Cacace et al., 1997; Miller and Hoseney,
2008).
References say that increasing salt addition decreases the water absorption capacity and increasing mixing time and dough
development time (Hlynka, 1962; Preston, 1989; Tanaka et al.,
1967). It also increases the strength of dough, what is proved by
baking tests as well. Lynch et al. (2009) found that the bread volume is not affected by its salt concentration, however, decreased
gas holding capacity of low salt dough was found and uneven
crumb structure of baked bread is also observed. Singh et al
(2002) also reported only a small decrease as the effect of salt
content reduction of dough; half amount of sodium chloride resulted only 8-10% volume loss, but its effect on the bread firmness was much more significant.
The aim of this study is to extend our knowledge on the
rheologic effects of salt. Alveograph test is a rheologic analysis
of dough and it uses 2.5% NaCl solution. To evaluate the effect
of sodium we used different salt forms and concentrations to reveal what are their effects on the alveograph parameters and
whether the use of other salts results the same or similar effects
on dough properties.
MATERIAL AND METHOD
The evaluated flour samples were BL55 ones and bought
from a local supermarket. The evaluated salt forms were sodium
chloride, potassium chloride, sodium acetate, potassium acetate
and calcium acetate (VWR, Belgium). The ion exchanged water
used for tests was performed by Millipore water purifier (Millipore, France).
Alveograph tests were performed by Alveograph NG (Chopin, France). All the analyses were done in the laboratory of
University of Debrecen, Faculty of Agricultural and Food Sciences and Environmental Management, Institute of Food Science
and the Agricultural Laboratory Centre.
Alveograph tests were performed by the MSZ EN ISO
27971:2008 standard. Salt solutions were prepared in 0.5; 1.0;
1.5; 2.0 and 25% w/v%. All the measurements were performed
in two repeats. The results were analyzed by one-way analysis of
variance using SPSS 15.0 for Windows statistical program package (SPSS Inc.) and Tukey’s post-hoc test was used to reveal
significant differences. The tables present means and standard
deviations.
RESULTS AND DISCUSSION
The alveograph parameters are generally influenced by the
added salt forms and concentrations (Table 1). The increasing
concentrations of sodium chloride significantly influenced the P,
L and P/L values and it can be seen that higher doses of salt
(more than 2%) resulted remarkable increase in the strength of
dough represented by the P value (maximum pressure). Simultaneously, increase in salt content resulted less extensible dough as
it can be seen in the decrease of L value (extensibility). These
Journal on Processing and Energy in Agriculture 18 (2014) 3
changes resulted a significant increase in the P/L ratio and the
values higher than 1 report good baking values. The changes
were not proved statistically in the case of the W value (deformation work), but a tendentious increase was experienced in the
case of 1.5 and 2% concentrations.
The effect of potassium chloride addition was also significant on the P, L and P/L values. The change was favourable considering recommended values for bread making to 1.5% with
regards to the maximum pressure and extensibility, but further
increase in salt concentration resulted decrease in P and P/L values. The W value did not changed significantly and in remarkable extent with the increase of added KCl.
In the case of sodium acetate the increasing concentrations
resulted significant changes in P and W values. This salt form
caused continuous increase in W value and in the P value up to
the 2% concentration, but while the effect on W value was favourable, the strength of dough was the lowest comparing to the
other salt forms. Besides, it significantly increased the extensibility of dough and as a result, very low P/L values were experienced.
The potassium acetate addition resulted relatively high P
values to the 4th treatment, but the 2.5% concentration caused
decrease. In the L values continuous and significant increase was
experienced and it resulted also continuous decrease in the P/L
value. The increasing potassium acetate concentration increased
the W value and resulted the highest readings in the experiment
at high concentrations.
The lowest L values were experienced with the use of calcium acetate but slight decrease was observed by the increasing
concentrations. In contrast, the low concentrations (0.5 and 1%)
resulted high P values therefore the P/L values of the first two
treatments were outstanding ones. Due to the low L values and
the decrease of P values the W values were the lowest ones in
comparison to the other salt forms.
Table 1. Alveograph properties of dough made from BL55
flour and different salt solutions
Conc.
w/v
0.5%
1.0%
1.5%
2.0%
2.5%
0.5%
1.0%
1.5%
2.0%
2.5%
0.5%
1.0%
1.5%
2.0%
2.5%
0.5%
1.0%
1.5%
2.0%
2.5%
0.5%
1.0%
1.5%
2.0%
2.5%
P, mm
L, mm
P/L
sodium chloride
60.8 ± 1.0 a 77.8 ± 17.4 a 0.83 ± 0.25 a
63.0 ± 2.7 a 73.5 ± 5.2 ab 0.86 ± 0.09 a
66.5 ± 1.7 a 71.8 ± 12.8 ab 0.95 ± 0.18 a
73.0 ± 3.4 b 67.8 ± 10.8 ab 1.10 ± 0.21 a
78.0 ± 4.1 b 49.8 ± 7.9 b
1.62 ± 0.36 b
potassium chloride
78.3 ± 3.6 a 53.8 ± 8.8 ab 1.50 ± 0.36 ab
79.0 ± 1.4 a 53.5 ± 7.0 ab 1.50 ± 0.23 ab
86.8 ± 3.0 b 41.3 ± 6.6 a
2.17 ± 0.44 b
60.8 ± 4.3 c 74.5 ± 17.9 b 0.88 ± 0.35 ab
67.3 ± 1.0 d 52.8 ± 4.2 ab 1.29 ± 0.12 a
sodium acetate
41.5 ± 1.7 a 84.0 ± 17.1 a 0.51 ± 0.10 a
46.0 ± 1.2 ab 97.3 ± 16.0 a 0.49 ± 0.08 a
50.8 ± 2.5 bc 83.8 ± 7.1 a
0.61 ± 0.07 a
58.0 ± 3.6 d 87.8 ± 20.7 a 0.71 ± 0.26 a
53.8 ± 1.3 cd 103.5 ± 6.4 a 0.52 ± 0.04 a
potassium acetate
69.3 ± 1.9 a
55.5 ± 3.3 a
1.26 ± 0.08 a
62.0 ± 1.8 b 64.8 ± 5.7 ab 0.96 ± 0.09 b
64.0 ± 2.4 b 76.5 ± 12.1 bc 0.85 ± 0.18 b
70.0 ± 1.0 c
84.7 ± 4.2 c
0.83 ± 0.05 b
54.0 ± 0.8 d 119.8 ± 9.2 d 0.45 ± 0.04 c
calcium acetate
96.3 ± 5.2 a
26.3 ± 6.4 a
3.87 ± 0.99 a
69.2 ± 6.1 ab 39.0 ± 12.6 ab 1.99 ± 0.78 b
55.3 ± 4.6 abc 47.8 ± 10.2 abc 1.20 ± 0.28 b
58.3 ± 3.9 c 64.8 ± 14.4 c 0.94 ± 0.27 b
63.0 ± 3.2 bc 52.8 ± 10.6 bc 1.24 ± 0.24 b
W, 10-4J
130.5 ± 17.2 a
138.5 ± 5.2 a
147.0 ± 19.0 a
159.3 ± 10.1 a
139.5 ± 11.5 a
138.5 ± 11.1 a
141.5 ± 9.8 a
133.0 ± 12.2 a
135.0 ± 16.8 a
123.5 ± 7.7 a
98.3 ± 9.5 a
114.8 ± 9.0 a
118.3 ± 6.1 ab
139.5 ± 16.8 bc
143.3 ± 5.5 c
122.3 ± 4.9 a
122.3 ± 6.7 a
138.0 ± 9.5 b
164.0 ± 2.6 c
162.8 ± 4.9 c
105.5 ± 15.3 a
95.4 ± 13.9 a
91.0 ± 7.8 a
112.5 ± 9.6 a
110.5 ± 16.3 a
127
Sipos, Péter et al. / Effects of Salt Forms and Concentrations on the Alveograph Parameters of Winter Wheat
Means marked with the same letter in the same column were
not significantly different at the 5% confidence level on the basis
of Tukey’s test.
CONCLUSION
Based on our results it can be concluded that both the salt
forms and concentrations influenced the alveograph values. In
the case of P values both sodium chloride and acetate resulted
slight but continuous increase while the use of potassium salts in
lower concentrations resulted similar values and the higher doses
resulted breakdown. Similar trend was found in the case of calcium acetate but in that case the rapid decrease was resulted by
the second concentration. Comparing these values to the one obtained by the standard alveograph test (2.5% NaCl concentration) it can be established that only the 0.5 and 1.0 % KCl resulted similar values; the maximum pressure values were lower
for most of the cases, but the 0.5% calcium acetate and 1.5% potassium acetate resulted higher reading, therefore more resistant
dough. The effects of applied salts were much moderate for the
L value, only the potassium acetate resulted visible and significant increase. The lower concentrations of sodium chloride resulted higher L values, therefore more extensible dough than the
standard concentration. Even lower values were caused by the
KCl (except the 2.0%) and the lower concentrations (0.5 and
1.0%) of calcium acetate and the smallest potassium acetate concentration, while the in the other cases the L readings were higher than the one obtained under standard conditions. The sodium
acetate addition resulted almost 2 times higher extensibility. The
W value was increased by sodium acetate and potassium acetate
in the highest degree. Comparing the salt forms and concentrations to the 2.5% NaCl it was found that only the high levels of
potassium acetate (2.0 and 2.5%) and the 2.0% sodium acetate
results significantly higher values, the potassium acetate in 2.5%
concentration similar, but the other set ups lower and significantly lower values for deformation energy. As all the evaluated salts
are allowed to use in bread making (the acetates as acidifying
agent and potassium chloride as salt substituent) the optimal
combination of these additives can result significant improvement in dough and therefore bread structure, but the evaluation
of the effects of these combinations both on the rheologic readings and bread properties require further tests.
Comparing the alveograph curves obtained by the different
salt form and concentrations.
ACKNOWLEDGMENT:This research was supported by the
European Union and the State of Hungary, co-financed by the
European Social Fund in the framework of TÁMOP-4.2.4.A/ 211/1-2012-0001 ‘National Excellence Program’.
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Journal on Processing and Energy in Agriculture 18 (2014) 3
Biblid: 1821-4487 (2014) 18; 3; p 129-133
UDK: 635.262
Original Scientific Paper
Originalni naučni rad
STUDY OF GARLIC ( Allium sativum L.) GROWING TECHNOLOGY
AND VARIETY TYPESUSED IN SERBIA AND IN HUNGARY
STUDIJA TEHNOLOGIJE PROIZVODNJE RAZLIČITIH VARIJETETA
BELOG LUKA U SRBIJI I MAĐARSKOJ
Zsuzsanna FÜSTÖS, Melanie KOVÁCS
Budapest Corvinus University , Department of Vegetable and Mushroom
Ménesi u.4.1118 Budapest, Hungary
e-mail: [email protected]
ABSTRACT
The garlic is grown and consumed from the age of pyramids in Egypt (2700-2100 BC ) as a food, spicy and a medicine . Garlic
production is high in Asia ( China the first), Latin America, North Africa and in Southern part of Europe. The world production area
1422428 ha, European 103348 ha. Serbia on the top of the 10 European country 7744 ha, In Hungary the garlic area decreased to
1048 ha. The garlic is very important in the Serbian and Hungarian meat industry and kitchen.The aim of the study was to survey the
level of growing technology and produced varieties in the garlic farms in the traditional region in Serbia Vojvodina (Vrbica, Torda,
Backo Petrovo Selo) and in Hungary Makó and Kalocsa. We analysed the answers of 20 questioners, filled in the farms. The most
important were from the 19 questions: - area of the farm, - size of garlic growing, -produced varieties, harvest method,-curing system , -storage method. We also tested the 33 different garlic bulb samples, collected from the farms. We measured the weight of bulb,
diameter, cloves number, pealing weight loss, dry material and sulphur content of the samples.We found the big differences in the
size of garlic growing area between the countries, in Serbia 0.3-2.8 ha, in Hungary 1-50 ha. The produced varieties in region Kalocsa, village Bátya and Vojvodina local varieties, in region Makó local and import (French , Spain) varieties. The harvest method,
curing system, storage method are similar. Only one farm Dombegyház includes the Makó region has complete mechanized garlic
growing, curing, store technology.The results of measuring of garlic bulb samples shown no direct correlation among the weight, diameter, cloves number, dry material of the samples. That characteristics genetically determined by variety characteristics. Between
weight of bulb and pealing weight loss have a close relationship. The conclusion of the results in the small farms alone can develop
the technology. The import varieties have a good quality and high yield, but the local varieties have a highest dry material and sulphur content.To keep the high value of the local varieties in the Serbia and in Hungary need a supported programme.
Key words: garlic production, curing, harvest; garlic varieties, quality parameters, inner contents.
REZIME
Beli luk se uzgaja i konzumira još iz perioda piramida u Egiptu (2700-2100 pne.) kao hrana, začin i lek. Proizvodnja belog luka
je visoka u Aziji (prvenstveno u Kini), latinskoj Americi, na severu Afrike i južnom delu Evrope. Proizvodnja belog luka na svetskom
nivou kreće se na površini od oko1422428 ha, a u Evropi na oko 103348 ha. Srbija je jedna od najvećih proizvođača belog luka u
Evropi na površini od oko 7744 ha, u Mađarskoj je ova površina manja i kreće se od oko 1048 ha. U Srbiji i Mađarskoj beli luk je
važan sastavni deo u industriji mesa i u domaćinstvima. Cilj ove studije jeste da se ispita nivo razvojnih tehnologija proizvodnje i
sorte belog luka koje se proizvode u tradicionalnim regionima u Srbiji, Vojvodini (Vrbica, Torda, Bačko Petrovo Selo) i u Mađarskoj
Makó i Kalocsa. Analizirani su odgovori 20 ispitanika, ispitivanih na farmama. Najznačajniji odgovori dobijeni su na osnovu 19 pitanja koji se odnose na: površinu farme, period razvoja belog luka, sorte koje se proizvode, metode ubiranja, tretmane zaštite, metode skladištenja. Takođe testirani su 33 različita uzorca lukovice, prikupljenih na farmama. Merena je masa lukovica, prečnik, broj
čenova, gubitak težine nakon čišćenja, sadržaj suve materije i sadržaj sumpora. Utvrđena je značajna razlika u širenju površine proizvodnje belog luka i u susednim zemljama, u Srbiji oko 0,3-2,8 ha, a u Mađarskoj 1-50 ha.Metode ubiranja, metode zaštite i metode
skladištenja su sličene. Te karakteristike definišu karakteristike sorte. Bliska povezanost uočena je između mase čenova i masenih
gubitaka nakon čišćenja. Zaključci dobijeni na osnovu ispitivanja malih farmi mogu da doprinesu razvoju tehnologija proizvodnje.
Uvozne sorte belog luka imaju visok kvalitet i dobar prinos, ali lokalne sorte imaju najveći ideo suve materije i sadržaj sumpora. Da
bi se sačuvala visoka vrednost domaćih sorti u Srbiji i Mađarskoj potrena je podrška razvojnih programa.
Ključne reči: proizvodnja belog luka, zaštita, ubiranje; sorte belog luka, parametric kvaliteta, unutrašni sadržaj.
INTRODUCTION
The garlic is grown and consumed from the age of pyramids
in Egypt (2700-2100 BC) as a food, spicy and a medicine. The
garlic is a queen of the spices, essential vegetable in the Serbian
and Hungarian meat industry and kitchen.
The history of using as a spice and medicinal plants is very
long and rich Scientific studies have shown pharmacological effects, there has been particular interest in benefits in the preven-
Journal on Processing and Energy in Agriculture 18 (2014) 3
tion and treatment of atherosclerosis and coronary heart disease.
Numerous tests of garlic extracts in vitro have demonstrated they
can aggregation of human body platelets to form cloth which
have to potential for arterial blocking (Block, 1985).
Marketed garlic mainly grown from cloves. During its cultivation history in different regions, garlic was adapted to various
climates and selected for cold resistance, bigger bulbs, or higher
pungency. In order to obtain a larger bulb, flower stalks were
often removed or clones with reduced flowering potential were
129
Füstös, Zsuzsanna et al./Study of Garlic (Allium Sativum L.) Growing Technology and Variety Typesused in Serbia and in Hungary
selected. The loss of garlic fertility, and today garlic varieties are
completely sterile. They don't produce seeds and are propagated
only vegetatively. In modern garlic varieties, the presence of
vegetative topsets (bulblets), which develop in garlic inflorescence, is one of the major causes of the inability of this plant to
develop normal flowers and true seeds (Kamenetsky, 2004/a)
A results of the long time research growing garlic from seed
offers the opportunity to produce new cultivars that enhance and
expand garlic’s genetic diversity. It also offers the prospect of
more vigorous and higher yielding plants that are free of pests,
viruses, and other diseases in the practice for consumption garlic
grown vegetatively from cloves (Etoh,1985).
At the end of the twentieth century several reports of fertile
garlic clones, both in the wild and in cultivation, initiated intense
interest in seed propagation of garlic, which appears to be a realistic proposition (Brewster, 1994).
Kamenetsky at al., (2004/b) have shown in their experiments
that the environmental conditions, especially temperature and
photoperiod, strongly affect garlic morphology and development, including leaf elongation, clove formation, and dormancy
induction and that the environmental regulatory effect is obligatory and yet quantitative.
The world production was decreasing in the last 10 years.
Garlic production is high in Asia (China the first), Latin America, North Africa and in Southern part of Europe (Table 1.).
Table 2. Garlic area and yield in Serbia
Year
Area (ha)
Yield (t/ha)
2006
8658
3
2007
8419
2.5
Serbia
2008
2009
8215
8113
2.9
2.9
2010
7867
2.8
2011
7744
2.7
2010
602
6.9
2011
1048
6.2
Table 3. Garlic area and yield in Hungary
Year
Area (ha)
Yield (t/ha)
2006
1122
6.5
2007
641
8
Hungary
2008
2009
636
636
7.4
7.4
MATERIAL AND METHOD
We studied to survey the level of growing technology and
produced varieties in the garlic farms in the traditional region in
Serbia Vojvodina (Vrbica, Torda, Backo Petrovo Selo) and in
Hungary Makó (includes Dombegyháza) and Bátya (region Kalocsa).
Table 1. Garlic production data in 2011
County
Area (ha)
World production
1422408
Europe
103348
China, mainland
827000
India
200600
Ukraine
21200
Egypt
12145
Spain
34900
Republic of Korea
43643
Romania
12128
Russian Federation
26800
Italy
3155
Myanmar
29194
Belarus
2454
Bangladesh
41997
Serbia
7744
United States of America
10180
France
2615
Argentina
17739
Albania
1586
Ukraine
21200
Republic of Moldova
2340
Hungary
1048
Source FAOSTAT
Yield (t/ha)
16
7
23
5
8
24
6
10
5
9
10
7
9
5
3
18
9
10
10
8
5
6
In the Hungarian National List have four garlic varieties Lelexir, (Makói tavaszi, (spring)) Makói őszi (autumn) Tibadúr,
Vigor supreme (Füstös, 2012). Selected varieties in Serbia ,
Bosut (autumn) , Labud (spring) (Gvozdanovic-Varga J. et al.
2009)
Beside the national listed varieties in the traditional garlic
production regions in the both countries grown local varieties. In
Hungary in the last years grown varieties from the EU Common
Catalogue. Varieties .
The main aim to study the reality and the problems of Garlic
production and usual current of varieties in two countries because the production in Hungary decreased, the average of yield
in Serbia is very low, see Tables 2 and 3.
130
Fig. 1. Map of the studied garlic regions
We analysed the answers of 20 questioners, included detailed
information of growing technology, economical problems, marketing of garlic. The questioners were filled in the farms during
of visit and study the system. The most important were from the
19 questions - area of the farm, - size of garlic growing, produced varieties, harvest method,- curing system, - storage
method. We evaluated the answers of that topics.
We also tested the 33 different garlic bulb samples, from the
38 collected samples from the farms. The varieties origined from
Serbian , Hungarian local selections French (FR) regitered varieties: Arno, Flavor, Cledor, Jolimont, Messidrome, Messidor and
from Spanish (E) registered varieties: Garpek, Gardacho, Garcua, Gardos (Table 8.)
RESULTS AND DISCUSSION
During evaluation of the questioners we have got a very colourful picture about the garlic production and farms. We have
shown only the main tendency of the results.
Table 4. The size of farms and part production area of garlic
growers
Size of farms (ha)
Serbia
Hungary
Smallest
0.3
2
Largest
12.5
2700
Garlic production area (ha)
Serbia
Hungary
Smallest
0.3
1
Largest
2.8
50
The size of studied farms and garlic fields small in both
countries but in Hungary have some bigger mechanised farm.
We have summarised the crop rotation used in garlic growing farms include as answer of the questioners.
Journal on Processing and Energy in Agriculture 18 (2014) 3
Füstös, Zsuzsanna et al./Study of Garlic (Allium Sativum L.) Growing Technology and Variety Typesused in Serbia and in Hungary
Table 5. Crop rotations
Crop rotation systems
Serbia
Hungary
1+1 year
1+3years
(garlic-barley)
(garlic -wheat)
2+2year
1+4year
(garlic -wheat-barley)
(garlic-maize-mustard,sunflower-wheat)
1+2 year
1+ 4 year
(garlic-sunflower-wheat)
(garlic-wheat-vegetable-maize-wheat)
2+5+1 years
1+5year
(garlic- clover - wheat) (garlic–petroselinum-pea-onion-maize-wheat)
1+3 year
1+4 year
(garlic – wheat)
(garlic- wheat )
1+2+1year
1+5 year
(garlic- maize-wheat)
(garlic wheat)
Crop rotation is very important in a vegetatively propagated
garlic production. The optimal rotation is longer than 5 year.
The autumn production is more safety and the potential yield
is higher. The grower used the same varieties both autumn and
spring time. The bulbs from the spring production have a better
quality and longer storage time.
Table 7.Variety type used in the different regions
Serbia
Backo Petrovo
Torda Vrbica
Selo
Bátya
Local
vatiety
Registerd
variety
*
*
*
*
Hungary
Makó Dombegyház
*
*
*
Table 6. The number of Autumn and Spring production of
tested garlic growing farms
Autumn
Spring
Autumn and Spring
Serbia
2
3
1
Hungary
3
0
11
Table 8. Summarised data of collected garlic samples (average of 10 bulbs)
Samples
Sz/1.
Sz/2.
Sz/3.
Sz/4.
Sz/5.
M/1.
M/2.
M/3.
M/4.
M/5.
M/6.
M/7.
M/8.
M/9.
M/10.
M/11.
M/13.
M/15.
M/16.
M/19.
B/1.
B/2.
B/3.
B/4.
B/5.
B/6.
B/7.
B/8.
B/9.
D/1.
D/2.
D/3.
D/4.
Planting season, variety
and origin of samples
Dry material con- SO₂ (mg/kg)
tent (m/m%)
Weight of
bulb(g)
Autumn, local, Torda
40.73
5.4
55.09
Autumn, local, Torda
36.83
0.9
75.48
Autumn, local, Backo Petrovo Selo
37.03
3.2
41.58
Spring, local, Vrbica
40.41
2.3
29.90
Spring, local, Vrbica
40.73
11.6
24.84
Spring, local Makó
39.97
2.6
41.46
Spring, Cleodor (FR)Makó
37.33
9.1
64.05
Spring, local Makó (no irrigation)
40.51
6.4
39.54
Spring, local Makó (with irrigation)
39.93
4.6
46.36
Autumn Flavor (FR)1. year Makó
38.76
14.2
50.40
Autumn Flavor (FR)2. year Makó
39.50
16.3
44.76
Spring, local Makó
40.41
13
44.98
Spring ArnoMakó
40.71
8.9
57.27
Autumn , local, ,Makó
38.99
5
59.93
Autumn, local,spring type Makó
38.56
21.6
42.91
Autumn Messidrom (FR)1.year Makó
38.70
10.4
60.60
Autumn Messidrom(FR) 2.yearMakó
34.52
1.1
72.33
Autumn, Makói őszi, Makó
38.61
0
50.17
Autumn (FR) Messidor, Makó
39.94
4.8
56.86
Autumn (FR) Jolimont, Makó
37.39
8.1
53.05
Autumn, local, Bátya
35.25
0
60.17
Autumn ,local, Bátya
38.28
3.3
61.04
Autumn, local, Bátya
38.26
0
61.49
Autumn, local, Bátya
34.97
3.4
58.50
Autumn, local,spring type , Bátya
40.86
4.1
55.90
Autumn, local,spring type , Bátya
38.78
3.3
25.96
Autumn, local, Bátya
39.03
1.6
57.29
Spring, local, Bátya
39.11
0
37.29
Spring, local, Bátya
39.73
0
32.34
Autumn, Garpek (E) Dombegyház
36.38
0.2
54.83
Autumn ,Gardacho (E) Dombegyház
38.22
5.1
61.09
Autumn, Garcua (E) Dombegyház
38.48
5.1
83.33
Autumn, Gardos (E) Dombegyház
39.58
0.7
53.25
* Sz/ Serbia, M/Makó, B/Bátya, D/Dombegyház
Journal on Processing and Energy in Agriculture 18 (2014) 3
Weight of
cloves
(g)
53.39
71.98
40.35
28.23
23.34
38.74
60.13
35.49
43.55
48.01
42.56
40.82
52.75
56.56
39.38
58.09
69.04
47.83
53.81
50.13
55.79
55.44
59.62
52.91
51.82
22.18
54.59
34.83
29.53
52.35
58.86
80.76
51.24
Number of
cloves/bulb
Diameter
(cm)
11.44
11.20
12.60
9.70
10.30
9.22
11.00
5.10
8.70
9.70
8.60
8.80
10.89
9.00
6.10
9.30
12.50
8.70
10.30
10.22
10.20
8.80
9.00
7.60
13.90
15.30
8.50
13.40
13.30
11.80
9.90
10.56
10.50
5.21
6.41
4.64
3.94
3.66
4.59
5.47
4.52
4.77
5.04
4.83
4.57
5.36
5.73
4.53
5.74
6.26
5.23
5.51
5.29
5.81
6.10
5.81
6.12
5.51
4.17
5.88
4.45
4.56
5.20
5.09
6.01
4.97
131
Füstös, Zsuzsanna et al./Study of Garlic (Allium Sativum L.) Growing Technology and Variety Typesused in Serbia and in Hungary
The collected and measured data has shown a high deviation
in the diameter and number of cloves. We found small bulbs
with a numerous cloves and opposite big bulbs with law number
of cloves.
43
42
41
Dry material (%)
7
6
5
Diameter (cm)
y = -0,060x + 41,63
R² = 0,236
40
39
38
37
4
36
3
35
2
y = -0,019x + 5,376
R² = 0,003
1
34
20
40
60
80
Weight of cloves/bulb (g)
0
4
6
8
10
12
Number of the cloves
14
16
Table 9. The rank of the garlic bulb weight of the tested
samples
Fig.2. Ratio between diameter and number
of cloves of garlic samples
Sample
The weight losses after peeling is connected to bulb weight
have a close relationship with weight of cloves/bulb.
90
Weight of cloves (g)
D/3.
Sz/2.
y = 0,979x - 1,974
R² = 0,993
80
Figure 4. Dry material content of different bulb weight
M/13.
M/2.
70
Planting season, variety
and origin of samples
Bulb Diameter Dry material
weight
(cm)
content
(g)
(m/m%)
Autumn, GarcuaE) Dom- 83.33
6.01
38.63
begyház
Autumn, local, Torda
75.48
6.41
36.96
Autumn Messidrom
72.33
(FR) 2.year Makó
Spring, Cleodor (FR)Makó 64.05
6.26
35.28
5.47
37.42
B/3.
Autumn, local, Bátya
61.49
5.81
38.24
60
D/2.
61.09
5.09
38.41
50
B/2.
Autumn ,Gardacho (E)
Dombegyház
Autumn ,local, Bátya
61.04
6.10
38.23
The data of sulphur content are not significant needed more
replication and compare with other method. We only publish as
informal information. The fact is on the top the local varieties
are standing.
40
30
20
Table 10. Sulphur content of the 5 top samples
10
0
20
40
60
Weight of bulb (g)
80
Sample
Planting season, variety and origin of samples
M/10.
M/6.
M/5.
M/7.
Sz/5.
Autumn, local, spring type Makó
Autumn Flavor (FR)2. year Makó
Autumn Flavor (FR)1. year Makó
Spring, local Makó
Spring, local, Vrbica
SO₂
(mg/kg)
21.6
16.3
14.2
13.0
11.6
Figure 3.Close connection of weight of bulb and cloves
We have got unaccepted results connected to bulb size,
weight and dry material content, the varieties with big size of
bulbs gave a high dry material content results too. Some small
size bulb had only medium dry material content.
Confirming our results the data of the first biggest bulb size
samples underscore the observations the varieties characterised
by big size and high yield can content high dry materials.
132
CONCLUSION
We found the big differences in the size of garlic growing
between the countries, in Serbia 0.3-2.8 ha, in Hungary 1-50 ha.
The produced varieties in region Kalocsa and Vojvodina local varieties, in region Makó local and registered (French,
Spain) varieties. The harvest method, curing system, storage
method are similar. Only one farm Dombegyház includes the
Makó region has complete mechanized garlic growing, artificial
ventilation curing, store technology.
Journal on Processing and Energy in Agriculture 18 (2014) 3
Füstös, Zsuzsanna et al./Study of Garlic (Allium Sativum L.) Growing Technology and Variety Typesused in Serbia and in Hungary
In our study we had similar opinion with Gvozdanovic-Varga
J. et al.2009 and Füstös 2012,
the yield has correlation with planting time and varieties but
has to introduce to the garlic growers the variety sortiment of EU
Common Catalogue for developing garlic production in both
countries.
The results of measuring of garlic bulb samples shown no
direct, close correlation
among the weight, diameter, cloves number, dry material of
the samples. That characteristics genetically determined by
variety characteristics.
Between weight of bulb and pealing weight loss have a
close relationship.
The conclusion of the evaluate the questioners in the small
farms alone can’ develop the technology. The import varieties
have a good quality and high yield. but the local varieties
sources of the highest dry material and sulphur content.
To keep the high value of the local varieties in the Serbia
and in Hungary need a supported common research programme
to save biodiversity of garlic.
REFERENCES
Block, E. (1985). The Chemistry of Garlic and
Onions. ScientificAmerican 252, 114–119.
Brewster, J. L. (1994). Onions and Other Vegetable
Alliums. Wallingford, U.K.: CAB International.
Etoh, T. (1985). Studies on the sterility in garlic. Allium
sativum L. Memoirs of the faculty of agriculture of Kagoshima
University 21, 77-132.
Füstös Zuzsanna. (2012) A fokhagymatermesztés szervezése
(Managing of garlic production), In Kiss Z. Versenyképes
Zöldségtermesztés
(Competative Vegetableproduction.),
Magyar Agrárkamara: 148-152.
Gvozdanovic- Varga J. et al. (2009). Prizvonja , belog lukas a
aspekta sadnog materijala. Novi Sad, Institut za rastarstvoi
povtarsto, Zbornik radova, Sveska 46, 2009:99-109.
Kamenetsky, R. (2004/a). True seeds in garlic. The Garlic
Newsletter, Canada, 2004, 2 (3), 4-5.
Kamenetsy, R. London Shafir, I., Zemah, H., Barzilay, A. and.
Rabinowitch H. D.( 2004/b). Environmental Control of Garlic
Growth and Florogenesis. Journal of the American Society for
Horticultural Science, 129, 144-15.
Received: 25. 03. 2014.
Journal on Processing and Energy in Agriculture 18 (2014) 3
Accepted: 30. 03. 2014.
133
Biblid: 1821-4487 (2014) 18; 3; p 134-136
UDK: 631.563:641.13:641.12
Original Scientific Paper
Originalni naučni rad
OPTIMAL CONTROL OF FRUIT AND
VEGETABLES DRYING PROCESS
OPTIMALNO UPRAVLJANJE PROCESOM
SUŠENJA VOĆA I POVRĆA
Dragan MATIĆ, Ilija KAMENKO, Perica NIKOLIĆ, Vladimir BUGARSKI
University of Novi Sad, Faculty of Technical Sciences, 21000 Novi Sad, Trg Dositeja Obradovića 6, Serbia
e-mail:[email protected]
ABSTRACT
In this paper is shown optimal auto-tuning procedure for tuning of temperature controller in a process of fruit and vegetables dehydration. The dehydrating process is the first order model with transport delay. For temperature control, a proportional-integralderivative controller is used. Optimization of controller is obtained by conducting relay feedback experiment, estimating the ultimate
gain and ultimate frequency based on which controller parameters are chosen. Performances obtained by auto-tuning procedure are
compared with Haalman’s procedure which is based on open loop experiment. When optimal temperature controller is used significant improvement of fruit and vegetables dehydrating process is achieved and more energy efficient system is obtained.
Key words: temperature control, optimal controller, dehydrating process.
REZIME
U ovom radu je dat prikaz procedure za automatsko podešavanje parametara regulatora temperature u procesu sušenja voća i
povrća. Proces sušenja je modelovan sistemom prvog reda sa transportnim kašnjenjem. Regulacija vlažnosti i brzine kretajna vazduha nije razmatrana, ove vrednosti su postavljene na 40% i 3 m/s respektivno. Za regulaciju temperature odabran je proporcionalnointegralni-diferencijalni regulator. Optimizacija parametara regulatora je izvršena izvođenjem eksperimenta u zatvorenoj povratnoj
sprezi primenom nelinearnog elementa (releja). Na ovaj način su estimirane vrednosti kritičnog pojačanja i frekvencije na osnovu
kojih se vrši sinteza parametara regulatora. Iz ovog razloga veoma je značajno da se kritično pojačanje i frekvencija odrede uz što
manju grešku. Jedan od načina da se poboljša estimacija ovih vrednosti je primena saturacijonog releja umesto idealnog releja. Performanse sistema dobijene primenom automatskog podešavanja parametara su upoređene sa rezultatima dobijenim primenom Haalman-ove procedure koja je zasnovana na izvođenju eksperimenta u otvorenoj sprezi. Kada je primenjen optimalni regulator temperature ostvaren je vidljiv napredak u performansama sušenja voća i povrća, ovakav sistem je energetski efikasan. Izvršena je komparativna analiza sistema na odskočnu pobudu kao i na pojavu poremećaja u iznosu od 15% od zadate vrednosti. Umanjen je preskok za
više od 20% uz očuvanje performansi u dinamici odziva, odnosno vreme uspona i vreme smirenja. Neke od prednosti primene metode
za automatsko podešavanje parametara regulatora su: projektovani regulator je optimalan, u toku sinteze ne prekida se regulaciona
petlja, ukoliko dođe do promene u parametrima modela jednostavno se ponovo izvrši podešavanje parametara regulatora. Metode za
automatsko podešavanje regulatora se mogu lako primeniti u praksi. Postoje komercijalni regulatori koji imaju mogućnost automatskog podešavanja parametara regulatora. Najveći broj proizvođača ipak ne otkriva detalje vezane za metod podešavanja regulatora.
Ključne reči: regulacija temperature, optimalni regulator, proces sušenja.
INTRODUCTION
Advances in fruit drying technology have led to the development of new methods for fruit and vegetables drying. Some
recent techniques include the use of microwave, infra-red, and
UV radiation to provide the drying energy. The process of drying is still mostly achieved by controlling an environment. Main
process variables are air temperature, flow and humidity (Babić
et al., 2011).
Commercial fruit dryers (mechanical dehydrators) should
provide a consistent and a steady production during all seasons
and weather conditions. A disadvantage of many dehydrators is
that they cannot preserve the natural color as when fruit and
vegetables are sundried. The market demands require preservation of natural color. Good results without the loss of fruit color
can be achieved if firstly, UV lights are applied (simulating the
sun-drying) and secondly the fruit and vegetables are inserted
into the dehydrator (Radojčin et al., 2011).
In the practical applications, poorly tuned control loops are
not rare. This can led to weak dehydrator performances and not
energy efficient systems. In this paper is shown auto-tuning pro-
134
cedure for temperature control loop tuning in the dehydrator system. This method can be also applied to the air-flow and humidity control loops.
The paper is organized into four sections. In second section,
drying process is described. In third section, design of optimal
air-temperature controller is discussed into details, and in the
final fourth section conclusion is made.
MATERIAL AND METHOD
A modern commercial mechanical dehydrator system is assembled of a drying chamber (or tunnel), shutters, fan, and thermal source (an electrical heater, hot-water pipeline…), Fig. 1.
Dehydration process is conducted in two phases. The first
phase one is characterized by fast rate of moisture loss followed
by second slower phase. When the fruit or vegetables surface is
moisture, water evaporates forming a thin boundary layer of
high-humidity air. The thickness of the layer determines the rate
of drying in the first phase. Movement of heated air from a fan
over the fruit or vegetables surface reduces the thickness of the
high-humidity layer, thus increasing the evaporation rate.
Journal on Processing and Energy in Agriculture 18 (2014) 3
Matić, Dragan et al. / Optimal Control of Fruit and Vegetables Drying Process
In the second phase of drying the rate of moisture loss falls.
The second phase begins when the rate of moisture movement to
the surface of the fruit is less than the rate of evaporation from
the surface.
As a temperature controller, a proportional-integralderivative (PID) controller is used. Transfer function of PID controller is given in (2). Where are: P - proportional gain, I integral gain, D - derivative gain, and N – filter coefficient
(Pavković et al., 2014).



1
N 
(2)
C ( s)  P 1  I  D
1
s

1 N 
s

Initial tuning of PID controller is set by Haalman’s procedure (Astrom and Hagglund, 1995). This procedure yields PID
parameters for FOPDT system as given in (3). Parameter values
are given in Tab.1., step and disturbance response are given in
Figs. 4. and 5. respectively.
P
Fig.1. Principal schematic of mechanical
dehydrator system
The speed of drying is limited by the rate at which moisture
can move through the fruit tissue. Under mechanical dehydration, the overall speed of drying depends on the relative humidity and the speed and temperature of air passing over the fruit or
vegetables being dried. These parameters need to be monitored
and controlled throughout the process, and inattention to any of
them can jeopardize the success of the entire process.
During evaporation if hot air, use for drying, continuously
circulate in the dehydrator it will be saturated by water vapor.
This will lead to ‘cooking’ instead of drying of fruit and vegetable being processed. To avoid this scenario relative humidity
must be kept below 40%.
The movement of air has two fundamental functions in the
drying process. It transfers the heat from the heather to the fruit
or vegetables (to provide the energy required to vaporize the water). Secondly, it transfers the moisture from inside the dehydrator to the outside atmosphere. Common air speed values are 3 to
5 m/s.
Air temperature is used to supply the heat required to evaporate fruit and vegetables moisture and to increase the moisturecarrying capacity of the air. For example, air at 60°C can carry
five times more moisture than air at 32°C. A relatively small volume of hot air is needed to carry moisture out of the dehydrator.
Additional heat is necessary to heat trays, compensate for heat
lost through insulation, and heat the fresh air required to maintain a low humidity. The maximum operating temperature is determined by the temperature at which coloration and flavors is
preserved and depends of fruit and vegetables being dried.
RESULTS AND DISCUSSION
In this paper, focus is set on temperature controller optimization. A system of mechanical dehydrator is model as a first order
lag with a dead time (FOPDT) as given in (1). The relative humidity is kept on 40% and the air speed on 3 m/s. The system
time constant is 10 s and the dead time is 12 s. Ration between
the dead time and the system time constant is 1.2. This type of
system can be challenging to control due to large dead time.
W (s) 
k
1.2
e  Ls 
e 12 s
s  1
10s  1
Journal on Processing and Energy in Agriculture 18 (2014) 3
(1)
2
1
, I
3L

(3)
Potential drawback of Haalman’s procedure is necessity for
FOPDT identification in open loop. An open loop experiment
yields parameters of FOPDT system, based on which PID controller is tuned. During the open loop, experiment there is no any
control of process variable. This kind of approach can be challenging to apply in practice especially if auto-tuning procedure is
required.
Alternative is to use auto-tuning procedure based on relay
feedback method. When PID controller is tuned, feedback loop
is preserved, Fig. 2. Nonlinear element (a relay), shown in Fig.
3, is used to produce non-dumped oscillations from which are
calculated ultimate gain and ultimate frequency. Based on this
values PID parameters are tuned (Zhang et al., 2012; Baykant et
al., 2013).
Fig. 2. Relay feedback
Fig. 3. Saturation relay
Optimal parameters of PID controller are obtained if ultimate
gain Ku and ultimate frequency ωu are identified with minimal
error rate. The procedure is summarized as follows (Yu, 2006).
1. Select the height of the relay h (upper and lower limits in
the manipulated input in the experiment).
2. Perform relay feedback tests:
a) Use an ideal relay (set the slope of the saturation relay to
a large value) to estimate Kp
4h 
ˆ
 Ku  
a  .

135
Matić, Dragan et al. / Optimal Control of Fruit and Vegetables Drying Process
Table 1. Parameters of controllers and system analysis
b) Calculate the slope of the saturation relay
k  1.4k min , k min  Kˆ u .


c) Continue the relay feedback experiment using the
turation relay with
k  1.4k min .
sa-
3. Find ωu from the relay feedback test and compute the
ultimate gain from (4).
Ku 
2 
a
2h 
a
a 
arcsin    
1    
a 
 a   a
 a   


(4)
Finally, PID parameters by Ziegler-Nichols are given in (5).
K
2
P 
2 

P  u , I  , D  u ,  Pu 
(5)
1.7
Pu
8 
u 
In Figs. 4. and 5. are given comparative step and disturbance
response of system given in (1) for tuned PID controllers. From
Fig. 4. can be seen that step response obtained by auto-tuning
procedure yields significantly lower overshot with preserved rise
time and settling time, when compared with Haalman’s procedure. Reduction of overshoot is over 20% which influences
energy efficiency.
Haalman’s method
Proportional (P)
0.56
Integral (I)
0.1
Derivative (D)
0
Filter coefficient (N)
100
Rise time
12.1 s
Settling time
109 s
Overshoot
30.2%
Peak
1.3
Gain margin
6.42 dB at 0.158 rad/s
Phase margin
65 deg. at 0.0606 rad/s
Closed loop stability
Stable
Auto-tuning
0.72
0.06
0.79
6.93
12.1 s
71.5 s
7.81%
1.08
5.86 dB at 0.13 rad/s
44.2 deg.at 0.07 rad/s
Stable
CONCLUSION
In this paper, it is shown an auto-tuning procedure for temperature control in a dehydrating process for fruit and vegetables
drying. In the engineering practice many control loops are poorly
tuned which yields weak system performances and poor energy
efficiency ratings. Well-tuned controller reduces overshoot and
maintains transient performances of the process. Auto-tuning
procedures, like shown in this paper, significantly improve overall performances of the process. They are relatively easy to implement and deploy in practice. Auto-tuning procedures are implemented in many industrial controllers and PLCs though manufacturers do not discuss implementation into details. In the engineering practice auto-tuning procedures should be used whenever is possible.
ACKNOWLEDGMENT: This work is part of the project
“Sušenje voća i povrća iz organske proizvodnje kombinovanom
tehnologijom”, the grant noumber: TR-31058, financed by “Ministarstvo prosvete, nauke i tehnološkog razvoja”, Rep. of Serbia.
REFERENCES
Fig. 4. Step response of tuned temperature controllers
In Fig. 5. are shown comparative disturbance responses of
system given in (1) for tuned PID controllers. Disturbance is
modeled as instant drop of process variable for 15%. This simulates environmental influences on dehydrating process. Both
controllers performed well, auto-tuned controller obtained lower
overshot and smaller settling time.
Fig. 5. Step and disturbance response of tuned controllers
PID parameters values and comparative analysis of system
performance is given in Table 1.
136
Alagoz, B. B., Ates, A., Yeroglu, C. (2013). Auto-tuning of PID
controller according to fractional-order reference model
approximation for DC rotor control. Mechatronics, 23(7), 789797.
Astrom, K., Hagglund T. (1995). PID Controllers, 2nd Edition,
Instrument Society of America.
Babić, M., Babić, Ljiljana, Radojčin, M., Pavkov I., Bogićević
M. (2011). Effect of combined technology of fruit and
vegetables drying on equipment designing. Journal on
Processing and Energy in Agriculture, 15(3), 160-164.
Konstantinos, G., Papadopoulos, Nikolaos, I. Margaris (2013).
Optimal automatic tuning of active damping PID regulators.
Journal of Process Control, 23(6), 905-915.
Pavković, D., Polak, S., Zorc, D. (2014). PID controller autotuning based on process step response and damping optimum
criterion. ISA Transactions, 53(1), 85-96.
Radojčin, M., Babić, M., Babić, Ljiljana, Pavkov, I., Stojanović
Č. (2011). Rupture force and color of quince during osmotic
drying. Journal on Processing and Energy in Agriculture,
23(6), 905-915.
Yu, C., C. (2006) Autotuning of PID Controllers, A Relay
Feedback Approach, 2nd Edition, Springer.
Zhang, S., Taft, C.W., Bentsman, J., Hussey, A., Petrus, B.
(2012). Simultaneous gains tuning in boiler/turbine PID-based
controller clusters using iterative feedback tuning
methodology. ISA Transactions, 51(5), 609-621.
Received: 05. 03. 2014.
Accepted: 26. 03. 2014.
Journal on Processing and Energy in Agriculture 18 (2014) 3
Biblid: 1821-4487 (2014) 18; 3; p 137-139
UDK: 542.934.8:582.794.1:531.3
Original Scientific Paper
Originalni naučni rad
MASS TRANSFER KINETICS AND EFFICIENCY OF OSMOTIC
DEHYDRATION OF CELERY LEAVES
KINETIKA PRENOSA MASE I EFIKASNOST OSMOTSKE
DEHIDRATACIJE LISTA CELERA
Milica NIĆETIN* , Lato PEZO** , Biljana LONČAR*, Vladimir FILIPOVIĆ*,
Tatjana KULJANIN*, Violeta KNEŽEVIĆ*, Danijela ŠUPUT*
*
University of Novi Sad, Faculty of Technology, Bulevar Cara Lazara 1, 21000 Novi Sad, Serbia,
**
University of Beograd, Institute of General and Physical Chemistry, Studentski trg 12-16, 1100, Beograd, Serbia
e-mail: [email protected]
ABSTRACT
This research was conducted in order to examine the mass transfer kinetics, during osmotic dehydration of celery leaves (Apium
graveolens) in two different osmotic solutions (sugar beet molasses and the mixed solution of sodium chloride and sucrose), under
atmospheric pressure, at room temperature. The significance of used hypertonic solutions and immersion time on the various kinetics
parameters (water loss, solid gain and dehydration efficiency index) were tested during the process, using Analysis of variance. Principal component analysis and Cluster analysis were used for characterization of different samples, and standard score analysis was
applied in optimal process parameters determination.
Key words: osmotic treatment, celery, sugar beet molasses, mass transfer kinetics.
REZIME
Ovo istraživanje je sprovedeno sa ciljem da se ispita kinetika prenosa mase za vreme osmotske dehidratacije lista celera (Apium
graveolens), u dva različita osmotska rastvora (melasa šećerne repe i vodeni rastvor saharoze i natrijum-hlorida), na sobnoj temperaturi i atmosferskom pritisku. Primenom analize varijansi, praćen je uticaj korišćenih hipertoničnih rastvora i vremena imerzije na
ispitivane kinetičke parametre (gubitak vode, prirast suve materije i koeficijent efikasnosti procesa). Analiza glavnih komponenata i
klaster analiza su korišćene za karakterizaciju različitih uzoraka, a standardna “score” analiza je primenjena za određivanje optimalnih procesnih parametara.
Ključne reči: osmotski tretman, celer, melasa šećerne repe, maseni transfer.
INTRODUCTION
It has been proved that celery is a rich source of antioxidant
nutrients and its cosumption has many health benefits, therefore
is recognized as a healthy plant and spice (Ježek et al., 2008).
But, its high water content (approximately 80%) is the main responsible for the growth of microorganisms, which causes the
perishable or damaging changes of the sensory and nutritive characteristics of celery after short period (Ježek et al., 2008; Vina
and Chaves, 2006). For this reason it is desirable to eliminate the
water, which can be achieved by different methods of preservation (Nistor et al., 2011). Preservation methods like drying, canning and freezing have been applied to prolong the shelf life of
foods, but these methods produce food products that are low in
quality compared to their original fresh state (Ratti, 2009). In
regard to the other preservation treatments osmotic treatment
(OT) has a noticeable advantages providing shelf-stable and
quality processed products, furthermore is environmentally acceptable and energy efficient process. (El-Aouar et al., 2006).
OT process involves partial removal of water from food by immersion in a concentrated hypertonic solution. Due to low energy consumption and mild temperatures, which is considered minimal processing, OT is suitable as a pretreatment for many
processes. OT improves nutritional, sensorial and functional
properties of food without changing its integrity (Sablani et al.,
2002; Koprivica et al., 2010). Mass transfer is caused by a difference in osmotic pressure: water outflow from product to solution, solute transfer from solution into the product, and leaching
out of the products own solutes. Mass transfer mechanism and
quality of final product are affected by many factors such as
composition and concentration of osmotic agents, immersion
time of the product in the solution, agitation /circulation of osmotic solution, operating temperature, solution to sample ratio,
nature and thickness of food material and pre-treatment (Ćurčić
et al., 2013). Great influence on the kinetics of water removal
and solid gain has the type of osmotic agent. Concentrated su-
Journal on Processing and Energy in Agriculture 18 (2014) 3
crose solution, sodium chloride solutions and their combinations
are usually used as hypertonic solution (Mišljenović et al., 2010).
The use of a ternary system (water/sugar/salt) in the osmotic
treatment of foodstuff has shown higher rates of water loss.
When the salt is added, even with solutions with low concentrations of solutes, the process is more effective (Rodrigues and
Fernandes, 2007).
Recent research has shown that use of sugar beet molasses as
a hypertonic solution improves OT processes (Lević et al., 2007)
Molasses is a byproduct of sugar production from sugar beet
which is no longer possible to get the crystal sugar by usual procedures of crystallization. However, due to a rich nutritive composition, over 200 nutritional valuable compounds, molasses as
raw material has found its application in processing and fermentative industries and as a supplement in feed production
(Mišljenović et al., 2010). High content of solids (around 80%)
provide high osmotic pressure in the molasses and maintains a
high transfer potential favorable to water loss during OT and
thus enhances the efficiency of this process. The application of
sugar beet molasses as osmotic agent has many advantages: it is
sensory acceptable, always accessible in large quantities and
cheap raw material (Filipović et al, 2012).The objective in this
study was to investigate the influence of immersion time and the
type of osmotic solution on the efficiency of OT process of celery leaves. For this purpose the quality of osmotically dried celery leaves produced at three different immersion time, using
two different osmotic solutions was examined. To assess the
quality of this products their water loss, solid gain and dehydration efficiency index have been determined. Experimental results
have been subjected to analysis of variance (ANOVA) to show
relations between applied assays. In order to enable more comprehensive comparison between investigated samples, standard
score (SS) has been introduced. Principal Component Analysis
(PCA) and Cluster Analysis (CA) have been applied to classify
and discriminate analysed samples.
137
Nićetin, Milica et al. / Mass Transfer Kinetics and Efficiency of Osmotic Dehydration of Celery Leaves
MATERIAL AND METHOD
Celery leaves (Apium graveolens) was purchased at local
market, shortly before the treatment, to be used in the fresh state.
Initial moisture content of celery leaves was 80.92 %. Before
the OT, celery leaves were cut into pieces of dimension nearly
1x1 cm. As hypertonic mediums two different solutions were
used. The first one, concentrated sugar beet molasses, with initial dry matter content of 80.00%, was obtained from the sugar
factory Pećinci, Serbia (in further text indicated as sugar beet
molasses). The second osmotic solution, mixed aqueous solution
of NaCl and sucrose, was made from sucrose in the quantity of
1.200 g/kg water, NaCl in the quantity of 350 g/kg water and
distilled water (in further text indicated as ternary solution). The
material to solution ratio of 1:20 (w/w) was used during all experiments. The samples of celery leaves were submerged in laboratory jars at room temperature of 20oC, under atmospheric pressure. The OT process was performed in a period of 0-5 h under
constant conditions. Samples were withdrawn from the osmotic
solution at determined intervals of time (1, 3, and 5 h), then
lightly washed with water and gently absorbed with paper towels
to remove adhering solution. All experiments were repeated
three times. Dry matter content of the fresh and treated samples
was determined by drying at 105oC for 24h in a heat chamber
(Instrumentaria Sutjeska, Croatia) until constant weight. All analytical measurements were carried out in accordance to AOAC
(2000). In order to follow the mass transfer kinetics of the OT,
three key process variables were measured: moisture content,
change in weight and change in the soluble solids. Based on the
experimental data, water loss (WL), and solid gain (SG), were
calculated, as described by Koprivica at al., 2010.
Important process parameters as a function of different type
of osmotic solution and dehydration time were analyzed using
the ANOVA. During ANOVA calculation, the independent variables were: immersion time (X1) - 1, 3 and 5h; the type of
osmotic solution (X2) - sugar beet molasses (1) and ternary
solution (2), and the dependent variables were the responses:
WL (Y1) and SG (Y2). Two mathematical models of the following form were developed to relate two responses (Y) to
two process variables (X):
2
Yk   k 0    ki X i , k=1-2,
(1)
i 1
where: βk0, βki are constant regression coefficients, k-index.
Min-max normalization is a technique which is commonly
applied for comparison of various characteristics of complex
samples determined using multiple assays, where samples are
classified on the basis of the ratio of raw data and extreme values
of the measurement used. Considering that the scale of the data
from various parameters concerning mass transfer (WL and SG)
are different, the data in each data set should be transformed
into normalized scores, in accordance with the following equations:
max xi  xi
i
(2)
xi  1 
, i ,
max xi  min xi
(PCA) and Cluster analysis (CA) have been applied successfully
to classify and discriminate the different samples. All statistical
analyses of the collected results have been performed using
StatSoft Statistica 10.0® software.
RESULTS AND DISCUSSION
Table 1 provides an overview on the average values and
standard deviations of WL and SG parameters, as a function of
different type of osmotic solution and dehydration time. Dehydration efficiency index-DEI (WL/SG ratio) were calculated and
shown in the table 1. This ratio is considered to best determine
optimal condition for the OT. High DEI ratios point to intensive
water removal from the samples accompanied with minimal
solid uptake.
Table 1. Experimental results for celery leaves during
osmotic treatment
Solution Time WL g/g ini- SG g/g initial
tial sample
sample
weight
weight
Sugar
1
0.28±0.00b 0.11±0.00a
d
beet
3
0.34±0.01
0.13±0.00b
a
molasses 5
0.49±0.02
0.16±0.00c
Ternary
1
0.32±0.01c 0.18±0.00d
solution
3
0.40±0.01e 0.20±0.00e
5
0.50±0.01a 0.24±0.00f
Polarity
+
-
DEI
SS
2.49±0.06b
2.65±0.05b
3.10±0.13d
1.75±0.03c
2.03±0.07a
2.11±0.03a
/
0.50
0.58
0.79
0.31
0.44
0.50
/
The results are presented as mean±SD; Different letter within
the same column indicate significant differences (p <0.05), according to Tukey’s test. Polarity: ‘+’ = the higher the better criteria, ‘−’ = the lower the better criteria
Because of the great difference in osmotic pressure between
hypertonic solution and the celery leaves tissue, loss of the water
was high at the beginning of the dehydration (0.32 g/g i.s.w. in
the ternary solution and 0.28 g/g i.s.w. in the sugar beet molasses).
But, it was observed that increase of the OT process time resulted in greater removal of water from the samples, regardless
of the type of solution. The highest value of WL was achieved in
the ternary solution, after 5 hours. (0.50 g/g i.s.w.). Table 1
shows that SG also increases with immersion time in both solutions. Greater increase in values of SG was noticed in the samples which were treated in ternary solution, as compared to those
treated with the molasses. Since, one of the objectives of OT is
to achieve as low as possible solid uptake, the most acceptable
value for SG was achieved by using molasses as solution (0.16
g/g i.s.w.), after 5 hours of osmotic process. The maximum value
of DEI that indicates the most efficient dehydration process was
3.10, achieved by immersion of celery leaves for 5 hours in sugar beet molasses.
Optimum OT conditions which define maximum WL with
lesser SG were determined using SS, Table 1.
In case of “the higher, the better” criteria, used for WL score
calculation,or:
max xi  xi
i
(3)
xi 
, i ,
max xi  min xi
Table 2. ANOVA table (sum of squares for each assay)
df
WL
SG
Solution
1
0.002**
0.008*
Immersion time
1
0.038*
0.002**
Error
3
0.001
0.001
r2
0.951
0.871
*
Significant at p<0.05 level, **Significant at p<0.10
level, 95% confidence limit, error terms have been found
statistically insignificant
In case of “the lower, the better” criteria, used for SG score
calculation.
Obtained data have been subjected to analysis of variance
(ANOVA) for the comparison of means, and significant differences are calculated according to post-hoc Tukey’s HSD (“honestly significant differences”) test at p<0.05 significant level,
95% confidence limit. In addition, principal component analysis
ANOVA analysis revealed that the linear terms contributed
substantially in all of the cases to generate a significant second
order polynomial (SOP) model. WL was significantly affected
by all process variables, and the main influential variable seems
to be the treatment time (statistically significant at p<0.05 level,
95% confidence level). The type of solution was also important for
i
i
138
i
i
Journal on Processing and Energy in Agriculture 18 (2014) 3
Nićetin, Milica et al. / Mass Transfer Kinetics and Efficiency of Osmotic Dehydration of Celery Leaves
Factor 2: 43.23%
WL calculation, statistically significant at p<0.10 level. SG was
more influenced by the type of used solution, statistically significant at p<0.05 level (better results were obtained using sugar beet
molasses solution). The impact of production time for evaluation
of SG was also observed, statistically significant at p<0.10 level.
Also shown in Table 2 is the residual variance where the lack
of fit variation represents other contributions except for the
first order terms. All SOP models had insignificant lack of fit
tests, which means that all the models represented the data
satisfactorily. A high r 2 is indicative that the variation was
accounted and that the data fitted satisfactorily to the proposed model (SOP in this case). The r 2 values for WL (0.951)
and SG (0.871), were found very satisfactory and showed the
good fitting of the model to experimental results.
Optimization of the OT is performed using Standard Score
Analysis, to ensure optimal processing conditions (with as low
as possible immersion time) yielding an acceptable product quality (with high WL and low SG), and a high throughput capacity.
The optimum OT conditions for celery leaves, dehydrated in
sugar beet molasses solution are obtained at immersion time of 5
h, solution concentration and temperature of 80% and 20°C. The
analysis of dissimilarities in WL and SG between the samples
was investigated by means of PCA (diagram on Fig. 1). PCA
diagram shows the superiority of molasses solution compared
to ternary solution, which is evident by the position of points
1, 2 and 3, and the direction of DEI vector. More appropriate
WL values were observed after more immersion time (points
3 and 6, according to direction of WL vector), while more
acceptable SG values were noticed for lesser immersion time
(points 1 and 2, according to the direction of SG vector).
Euclidean distances were used as the measure of proximity
between different samples, used to draw the CA dendrogram
(Fig. 2).
3
DEI
WL
3
2
1
6
0
2
SG
5
-1
1
4
-2
-3
-2
-1 0
1
2
Factor 1: 56.73%
Fig. 1. PCA biplot diagram
3
Lincage distance
0.6
0.5
0.4
0.3
0.2
0.1
4
3
6
5
2
Samples
Fig. 2. CA dendogram
1
CONCLUSION
On the basis of presented results it can be concluded that
both solutions are satisfying osmotic mediums, taking into account the considerable loss of water during both processes. Optimal solution for drying celery leaves was sugar beet molasses and optimum process parameter was immersion time of
Journal on Processing and Energy in Agriculture 18 (2014) 3
5 h. The predicted responses for the optimum dehydration
conditions in sugar beet molasses were: WL about of 0.49 and
SG about 0.16 g/g i.s.w. (DEI=3.10, SS=0.69). Despite the fact
that sugar beet molasses proved to be more effective osmotic
solution, its use is justified also from environmental and economic aspects, because molasses is side product of sugar industry. Since both osmotic treatments carried out at room temperature, without the need of extra input of energy, it can be concluded that this is energy and economically favorable method of
preservation.
ACKNOWLEDGMENT: These results are a part of project
supported by the Ministry of Science and Technological Development of the Republic of Serbia, TR-31055, 2011-2014.
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tretman oblikovanog korena mrkve u saharozi i melasi. Journal
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Ćurčić, Biljana, Filipović, V., Nićetin, Milica (2012).
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Sablani S.S., Rahman, M.S., & Al-Sadeiri, D.S. (2002).
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Received: 12. 03. 2014.
Accepted: 28. 03. 2014.
139
List of the Permanent Reviewers
LIST OF PERMANENT REVIEWER – Journal on Processing and Energy in Agriculture
LISTA STALNIH RECENZENATA - Časopis za procesnu tehniku i energetiku u poljoprivredi
Prof. Dr. Costas Akritidis, Greece, Emeritus Professor, Department of Hydraulics, Soil Science and Agric. Engineering.
School of Agriculture. University of Thessaloniki Greece Drying,
Prof. Dr. Babić Mirko, Faculty of Agriculture, University of Novi Sad, Head of Department of Agricultural engineering,
Head of Laboratory of Biosystem Engineering, General
Secretary of National Society of Processing and Energy in
Agriculture - Postharvesting, Physical properties of Agricultural Materials, Renewable Energy,
Prof. Dr. Babić Ljiljana, Faculty of Agriculture, University of
Novi Sad, Vice-president of National Society of Processing
and Energy in Agriculture - Postharvesting, Physical properties of Agricultural Materials, Renewable Energy,
Prof. Dr. Haris Lazarides, Greece, Head of Department Food
Science and Technology - Food Processing & Engineering,
Prof. Dr. Milica Radosavljević, Maize Research Institute “Zemun Polje”, Belgrade, Vice-president of National Society
of Processing and Energy in Agriculture - Cereal
processing and food quality,
Prof. Dr. Mirjana Đurić, Faculty of Technology, University of
Novi Sad, Thermodynamics Prof. Dr. Silva Cristina, Portugal, Portuguese Catholic University, President of I ISEKI-Food Association - Design and Optimization of Food
Process Conditions,
Prof. Dr. Miloš Tešić, Faculty of Technical Science, Novi Sad,
Member of Vojvodina Academy of Sciences and Arts Agricultural Engineering, Renewable energy,
Dr. Gerhard Schleining, Austria, BOKU, Wiena, Secretary General of ISEKI-Food Association - Quality Management,
Functional Properties of Food and Food Technology,
Prof. Dr. Tajana Krička, Croatia, Faculty of Agronomy, Zagreb Postharvesting, Biomass and Biofuel from Agriculture,
Prof. Dr. Zuzana Hlavačova, Slovakia, Department of Physics,
Faculty of Agricultural Engineering, Slovak University of
Agriculture in Nitra, Vice-Dean of Faculty of Agricultural
Engineering - Physical Properties of Food and Agricultural Materials,
Prof. Dr. Anđelko Bajkin, Faculty of Agriculture, University of
Novi Sad - Horticulture Engineering,
Prof. Dr. Zsuzsanna Fustos, Hungary, Head of Department Central Agricultural Office; University of Horticulture and
Food Science, Budapest, ISHS - President of Vegetable
Section in Hungary - Testing of Food and Agricultural
Products,
Prof. Dr. Marko Dalla Rosa, Italy, President of the Degree
Course Committee on Food science and Technology at
University of Bologna, site of Cesena, Member of the Advisory Committee of ISEKI – Food Processing,
Prof. Dr. Richard Gladon, USA, Department of Horticulture,
Iowa State University - Postharvest Technology of Horticultural Products,
Prof. Dr. Elisabeth Demoulin, France, Food process engineering
at Ecole Nationale Supérieure des Industries Agroalimentaires (ENSIA) changed in Agroparistech (1er January
2007), in Massy, Member of ISEKI Board - Food Engineering,
Prof. Dr. Costas Biliaderis, Greece, Head of Laboratory of Food
Chemistry - Biochemistry, Dept. of Food Science & Tech-
140
nology, Faculty of Agriculture, Aristotle University of
Thessaloniki - Food Chemistry,
Prof. Dr. Janos Beke, Hungary, Vice-rector Szent István University Gödöllő, Hungary - Drying and Storage Agricultural
Materials,
Dr. Vlasta Vozarova, Slovakia, Nitra, Head of Department of
Physics, Faculty of Agricultural Engineering, Slovak University of Agriculture in Nitra - Physical Properties of
Food and Agricultural Materials,
Prof. Dr. Vangelče Mitrevski, FYR Macedonia, Head of Department of Mechanical Engineering, Faculty of Technical
Sciences, Bitola - Drying,
Dr. Stavros Vougioukas, Greece, Dept. Of Hydraulics, Soil
Science and Agricultural Engineering, Aristotle University
of Thessaloniki - Automatic Control and Sensing,
Dr. Jasna Mastilović, Institute for Food Technology, University
of Novi Sad - Feed Technology and Quality,
Prof. Dr. Mirjana Milošević, Institute of Field and Vegetable
Crops, Novi Sad,Seed Production and Testing,
Prof. Dr. Dušan Milić, Faculty of Agriculture, University of Novi Sad – Management and Economy of Fruit and Grape
production,
Prof. Dr. Filip Kulić, Faculty of Technical Science, University of
Novi Sad - Automatic Control,
Prof. Dr. Dragan Marković, Mechanical Faculty, University of
Belgrade - Designing in Agricultural Engineering,
Prof. Dr. Cecilia Hodur, University of Szeged, Institute of
Mechanical and Process Engineering, Hungary, Process
engineering,
Prof. Dr. Nebojša Novković - Faculty of Agriculture, University
of Novi Sad – Planning and Management in Agriculture,
Dr. Neven Voća, Croatia, Faculty of Agronomy, Zagreb - Postharvesting, Biomass and Biofuel from Agriculture,
Dr. Bojana Filipčev, Institute for Food Technology, University
of Novi Sad, Cereal processing, Quality and Properties of
Cereal Products,
Dr. Lubomir Kubik, Slovakia, Nitra, Faculty of Agricultural Engineering, Slovak University of Agriculture in Nitra Physical Properties of Food and Agricultural Materials,
Dr. Milka Vujaković, Poljoprivredna stanica, Novi Sad, Physical Properties of Agricultural Materials,
Dr. Sandra Voća, Croatia, Faculty of Agronomy, Zagreb - Postharvesting and Processing horticultural products,
Dr. Maša Bukurov, Faculty of Technical Science, University of
Novi Sad – Mechanics of Fluid, Fluid Plant Engineering,
Dr. Miodrag Zoranović - Faculty of Agriculture, University of
Novi Sad – Cattle Engineering, Microclimate Engineering,
Dr. Branislav Karadžić, Faculty of Agriculture, Novi Sad - Automatic Control, Information technology,
Dr. Aleksandra Dimitrijević, Faculty of Agriculture, Zemun –
Beograd, Agriculture Engeenering,
Dr. Ponjičan Ondrej, Faculty of Agriculture, Novi Sad, Agriculture Engeenering and
Dr. Ivan Pavkov, Faculty of Agriculture, Novi Sad, - Postharvesting , Physical Properties of Agricultural Materials,
Renewable Energy
The editorial board can also contact other reviewers if an article
is from a specific science area.
Redakcija može da pozove i druge recenzente ako je rad iz
specifične naučne oblasti.
Journal on Processing and Energy in Agriculture 18 (2014)
INFORMACIJE
SPORTSKI REZULTATI SA INOPTEP-A 2013
Tokom III međunarodne konferencije „Održive posleubirajuće i prehrambene tehnologije INOPTEP 2013“ i XXV nacionalne
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održana sportska takmičenja. Ostvareni su sledeći rezultati:
Konopac muškarci:
1.
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2.
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Pikado dame:
1.
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2.
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3.
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Pikado muškarci:
1.
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2.
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3.
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Kamena s ramena (dame):
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konferencije „Procesna tehnika i energetika u poljoprivredi PTEP 2013“ koja je održana u Vrnjačkoj Banji, izabran je i nagrađen
najbolji poster, najbolji mladi autor, najbolji prezenter i najinteresantnije izlaganje.
NAJBOLJI POSTER
Autori: Ondrej Ponjičan, Mirko Babić, Milivoj Radojčin, Anđelko Bajkin, Dragi Radomirović, Poljoprivredni fakultet Novi
Sad: PROMENE FIZIČKIH OSOBINA KORENA CELERA TOKOM OSMOTSKOG SUŠENJA
Pohvaljeni:
Miona Belović, Institut za prehrambene tehnologije, Novi Sad,
Dorota Kregiel, Tehnološki univerzitet, Lodz, Poljska.
NAJBOLJI MLADI AUTOR
Jelena Pejin, Olgica Grujić, Miloš Radosavljević, Sunčica Kocić-Tanackov, Tehnološki fakultet Novi Sad: UPOTREBA
TRITIKALA SORTE ADONIS KAO ZAMENE ZA JEČMENI SLAD U PROIZVODNJI SLADOVINE
Pohvaljeni:
Aleksandra Đukić-Vuković, Tehnološko-metalurški fakultet, Beograd.
NAJBOLJI PREZENTER
Vangelče Mitrevski, Ljupčo Trajčevski, Vladimir Mijakovski, Monika Lutovska, Fakultet tehničkih nauka, Bitolj,
Makedonija: OCENA NEKIH MODELA KINETIKE SUŠENJA
Journal on Processing and Energy in Agriculture 18(2014) 3
D1
NAJINTERESANTNIJE IZLAGANJE
Branimir Šimić, Goran Krizmanić, Luka Andrić, Josip Šimenić, Poljoprivredni institut Osijek, Hrvatska: ZNAČAJ I
USLOVI SKLADIŠTENJA TRETIRANOG SEMENA NA ENERGIJU KLIJANJA I KLIJAVOST HIBRIDA SUNCOKRETA
Pohvaljeni:
Željko Kanović, Fakultet tehničkih nauka, Novi Sad,
Sonja Gvozdenac, Poljoprivredni fakultet, Novi Sad.
Odluke o nagrađenim autorima donela je komisija u sastavu: Danka Dujović, Slavko Ivanišević, Filip Kulić, Milica
Radosavljević, Mirko Babić, Maša Bukurov.
Radno predsedništvo svečanog otvaranja 3. Međunarodne konferencije INOPTEP 2013
ODBRANJENA DOKTORSKA DISERTACIJA
Dana, 27.09.2013. na Tehnološkom fakultetu Univerziteta
u Novom Sadu, odbranjena je doktorska disertacija kandidata
Gordane Koprivice pod nazivom:
NUTRITIVNI PROFIL I SENZORSKI KVALITET
VOĆA I POVRĆA OSMOTSKI DEHIDRIRANOG U
MELASI
ŠEĆERNE
REPE
I
RASTVORIMA
SAHAROZE
Komisija u sastavu: dr Lidija Jevrić, Tehnološki fakultet,
Novi Sad (predsednik komisije); dr Ivan Pavkov, Poljoprivredni fakultet, Novi Sad (član); dr Lato Pezo, Institut za
opštu i fizičku hemiju, Beograd (član) i dr Ljubinko Lević,
Tehnološki fakultet, Novi Sad (mentor rada) je konstatovala
da doktorska disertacija sadrži sve elemente neophodne za
sagledavanje problematike i razumevanje dobijenih rezultata.
Komisija navodi da doktorska disertacija predstavlja originalan doprinos nauci, jer je dokazana mogućnost primene melase šećerne repe kao hipertoničnog rastvora u procesu osmotske dehidratacije voća i povrća. Sa stanovišta ispitivanja
nutritivnog i senzorskog kvaliteta osmotski dehidriranog voća
i povrća, utvrđena je prednost primene melase šećerne repe
kao osmotskog rastvora, umesto rastvora saharoze koji se
uglavnom koriste u procesu osmotske dehidratacije voća i
povrća.
Dipl. inž. GordanaKoprivica je rođena 16.05.1983. godine
u Gračanici, BiH. Gimnaziju, opšti smer, završila je 2001.
godine u Gacku (Republika Srpska). Iste godine upisala se na
Tehnološki fakultet u NovomSadu, smer Konzervisana hrana.
Studije na Tehnološkom fakultetu završava u predviđenom
roku sa prosečnom ocenom 8,81.
Od novembra 2007. do februara 2008. godine je bila zaposlena u mesnoj industriji “Matijevic”, kao tehnolog u
pogonu.
Od februara 2008. godine se zapošljavana Tehnološkom
fakultetu u Novom Sadu, najpre kao istraživač pripravnik,
a zatim i istraživač saradnik na projektima Ministarstva za
prosvetu i nauku Republike Srbije. Iste godine upisuje i doktorske studije u okviru programa Prehrambeno-biotehnološke
nauke. Tokom doktorskih studija polaže sve predviđene ispite
sa prosečnom ocenom10. Autor i koautor je preko 30 naučnih
radova od kojih je 6 međunarodnog značaja. Učestvovala je
na nekoliko međunarodnih i nacionalnih konferencija. Sa
timom naučnika sa Tehnološkog fakulteta 2009. godine, na
Takmičenju za najbolju tehnološku inovaciju, osvaja prvo
mesto u oblasti fizika/hemija u kategoriji ”Potencijali”. Pored
istraživačkih aktivnosti od 2010. do 2014. godine je bila
angažovana kao saradnik u nastavi na predmetima “Projektovanje tehnoloskih procesa” i “Procesna energetika”. Koautor
je zbirke zadataka “Projektovanje tehnoloških procesa –
Tehnološko – hemijski proračuni”. Govori engleski jezik.
Dr Gordana Koprivica
D2
Journal on Processing and Energy in Agriculture 18(2014) 3
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