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UDCUDCUDCUDC 663.951663.951663.951663.951+66.061+66.047:678.048+66.061+66.047:678.048+66.061+66.047:678.048+66.061+66.047:678.048 ScientificScientificScientificScientific paperpaperpaperpaper

EXTRACTIONEXTRACTIONEXTRACTIONEXTRACTIONOFOFOFOF GREENGREENGREENGREEN TEATEATEATEA ANDANDANDAND DRYINGDRYINGDRYINGDRYINGWITHWITHWITHWITHAAAAHIGHHIGHHIGHHIGHPRESSUREPRESSUREPRESSUREPRESSURE SPRAYSPRAYSPRAYSPRAY PROCESSPROCESSPROCESSPROCESS

DarjaDarjaDarjaDarjaMetercMetercMetercMeterc1111,,,, MarcusMarcusMarcusMarcus PetermannPetermannPetermannPetermann2222,,,, EckhardEckhardEckhardEckhardWeidnerWeidnerWeidnerWeidner11111Chair for Process Technology

2Chair for Particle Technology and Particle Design(Ruhr University Bochum), Bochum, Germany

Green tea is a widely consumed beverage throughout the world and is produced fromnon-fermented leaves of Camellia Sinensis. Traditionally, green tea leaves areextracted with water. To form solid products, these aqueous products have to be dried.The main focus of the investigation is how to avoid antioxidant degradation duringsolvent removal.The work was separated in two major sections, firstly investigation of the extractionprocess; secondly, optimizing of the drying process.In first experiments, extractions with different solvents (H2O, EtOH and MeOH), atdifferent temperatures (20, 40, 60 and 80 °C) and extraction times (15, 30, 60, 90 and120 min) were preformed to obtain optimum conditions for further processing. Forfurther work extracts obtained with water extraction at 80 °C for 15 min were used.In the PGSS (Particles from Gas Saturated Solutions) drying process, extracts with upto 98 wt % water are mixed with preheated carbon dioxide in a static mixer in order toobtain a homogenous mixture. The mixture is led via a single path nozzle into a spraytower. Driven by the expansion of the gas, fine droplets are formed and the heated gasevaporates the solvent, which is exhausted together with CO2 by a blower. Fine powderis formed and collected in the spray tower. The amount of solvent which is to beremoved and the residual humidity obtained in the product depend strongly on flowrate and temperature of the gas.From obtained results it can be seen, that high pre-expansion temperatures Tp (145 °C)cause degradation of polyphenols (1.05 wt %). Maintaining Tp at approximately 130°C and lower, gave satisfying results; total amount of polyphenols in the obtainedpowders was between 4.97 and 8.77 wt %. Temperature in spray tower ranging from33 to 65 °C has no significant effect on the amount of total polyphenols, but highertemperature results in lower water residue in the sample.Keywords:Keywords:Keywords:Keywords: PGSS Drying, Extraction, Green tea, Antioxidants

1.1.1.1. IntroductionIntroductionIntroductionIntroductionTea bush, also known as Camellia sinensis originates several thousand years ago fromthe area of Southwestern China [1]. One of the most important processes in tea

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manufacturing is fermentation. It is known that the conversion of tannin in tea leaves isnot achieved by microorganisms but by the enzymes present in the leaves. The degreeof fermentation greatly affects the quality and the type of tea. According to the degreeof fermentation, tea is classified into green tea (unfermented), oo-long (semi-fermented)and black tea (fully fermented) [2].One of the most important ingredients of tea leaves are polyphenols, which can befound in the highest concentrations in the green tea. The slight astringent and bittertaste of the water infusion is attributed to them. The contents of green tea polyphenols,which are composed of seven kinds of catechins and their derivatives slightly deviatesdepending on the species of tea plant and the season of harvesting [2]. Catechins aredivided into two classes: the free catechins, (+)-catechin (C), (+)-gallocatechin (GC),(-) -epicatechin (EC), (-)-epigallocatechin (EGC); and the esterified or galloylcatechins, (-)-epicatechin gallate (ECG), (-)-epigallocatechin gallate (EGCG), (-)-gallocatechin gallate (GCG) [1]. (-)-epigallocatechin gallate (EGCG), the most potentantioxidant of the polyphenol type of tea, is at least 100 times more effective thanvitamin C and 25 times more effective than vitamin E. EGCG is the major componentof the polyphenolic fraction of green tea. It makes up about 10−50% of the total greentea catechins. The antioxidant activity increases in the following order:EC<ECG<EGC<EGCG.A number of papers have been published on the antimutagenic activity, suppressiveeffect of chromosome aberration, antioxidant activity, depressor effect on arterialhypertension, inhibitory effect on lipid peroxidation, or inhibitory effects onarteriosclerosis, of the green tea polyphenols [3-8].Other components present in green tea are caffeine (1-5%), fats (4-16%), amino acids,sterols, vitamins, minerals, flavour and aroma chemicals, proteins, terpenoids andothers [2,9,10, 11-13].Green tea active ingredients, caffeine and polyphenols, are usually isolated from rawmaterial by extraction with different organic solvents or water.For this experiments water, methanol and ethanol were used as solvent. By changingsolvent, temperature, time of extraction and ratio of material to solvent; influence ofthis parameter on extraction yield and amount of extracted polyphenols as well ascaffeine was studied. Main interest for comparing different solvents was to increase theamount of extracted active ingredients in final product.The solvent is then removed by different processes among which spray or freezedrying prevail.As an alternative to those processes a new high pressure process for the gentle dryingof natural extracts has been used, due to degradation of polyphenols in aqueoussolution and their temperature sensitivity.The process is based on a high pressure spray technique called PGSS (Particles fromGas Saturated Solutions).Since polyphenols tend to degrade in water, water residue of powders is an importantparameter, which allows predicting the stability of product. Furthermore, low waterresidue extends the shelf life of product, by preventing growth of microorganisms.

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The analysis of green tea extracts were focused on the determination of the epicatechin,epicatechin gallate and epigallocatechin gallate. Additionally the content of thealkaloid caffeine was determined.

2.2.2.2. MaterialsMaterialsMaterialsMaterials andandandand methodsmethodsmethodsmethods2.1.2.1.2.1.2.1. MaterialsMaterialsMaterialsMaterialsDry green tea leaves were supplied by U Max (Chookbuk, Korea); some properties ofthe tea raw material are presented in

TableTableTableTable 1111. Reference substances were purchased from Sigma Chemical Co. All solventsfor extraction and analytical purposes were purchased from Merck.2.1.2.1.2.1.2.1. SampleSampleSampleSample analyzesanalyzesanalyzesanalyzesCatechins and caffeine were determined with high performance liquid chromatography(HPLC) - diode array detection technique (DAD).0.20 g of the extract is put into a 25 ml flask. As a solvent, a mixture of 30% bidistilledwater and 70% of acetonitril is used and filled to the mark on the flask. The mixture isplaced for 10 minutes into the ultrasound bath and/or stirred for 10 minutes. Before themeasurement of the sample by means of HPLC, the solution is filtered over adiaphragm filter.The evaluation of active ingredients of the samples is carried out over correspondingcalibration curve of standards.Particle size and particle size distribution of ground material and samples obtained byPGSS drying were measured with a laser diffraction method. The morphologies of theparticles were examined with a scanning electron microscope (SEM).Moisture content of samples was measured by a Mettler Toledo DL31 Karl FischerTitrator.

TableTableTableTable 1111:::: Composition, particle size and size distribution of raw materialRaw material

Humidity [%] 2.79 EC [g/100 g dry raw material] 0.97Median particle size [µm] 669 EGCG [g/100 g dry raw material] 3.92Mean particle size [µm] 745 ECG [g/100 g dry raw material] 1.41

2.2.2.2.2.2.2.2. ExtractionExtractionExtractionExtraction procedureprocedureprocedureprocedureThe experiments conducted for the extraction can be divided into two different sections.The extraction of green tea was performed with water, methanol and ethanol, atdifferent temperatures and mixing times as well as different mass ratios of green teaversus solvent. The solution was then filtered with Sartorius filter paper Nr. 288. Ineach experiment 20 g of ground green tea material was used.Extractions and sample analyzes were focused on determination of three majorpolyphenols; caffeine was determined in addition.

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2.3.2.3.2.3.2.3. PrinciplesPrinciplesPrinciplesPrinciples ofofofof thethethethe PGSSPGSSPGSSPGSS DryingDryingDryingDrying processprocessprocessprocessIn Figure 1 the flow scheme of the PGSS drying pilot plant is shown. The maximumoperating pressure of the plant is 200 bar and the maximum operation temperature is250 °C. The solution can be heated in a vessel and is conveyed with a piston pump.The vessel is placed on a platform balance in order to determine the mass flow of thegreen tea solution, which can be adjusted to a maximum of 5 kg/h.Carbon dioxide is stored at about 50 bar in a high pressure tank and taken as liquidfrom the tank with a diaphragm pump. The carbon dioxide mass flow is measured witha coriolis flow meter and can be varied between 10 and 60 kg/h. Subsequently the gasis heated in a tube coil heat exchanger. Carbon dioxide is led through an oneway valveinto the static mixer where it contacts with the solution to be dried.

a) b)FigureFigureFigureFigure 1111:::: (a) Flow scheme of the pilot plant and ( b) static mixer

Due to the construction of the mixing elements (right side of Figure 1) the solution andthe supercritical carbon dioxide are homogenized under high pressure and elevatedtemperatures. During the mixing supercritical carbon dioxide is partly dissolved in thegreen tea solution and the mixture is sprayed by a single path nozzle into a spray tower.Driven by the expansion of the gas, fine droplets are formed, and the heated gasevaporates the solvent, which is exhausted together with CO2 by a blower. Theobtained powder is collected at the bottom of the spray tower.To achieve a good solvent separation, it is important to know the solubility of thesolvent in carbon dioxide under spray tower conditions.

3.3.3.3. ResultsResultsResultsResults andandandand discussiondiscussiondiscussiondiscussion3.1.3.1.3.1.3.1. ExtractionExtractionExtractionExtraction andandandand dryingdryingdryingdrying underunderunderunder vacuumvacuumvacuumvacuum

The extracts were first dried under vacuum to be stabilized and then analysed.a) Water extraction with different ratios of raw material to mass of solvent:

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In the first experiments the influence of ratio raw material/solvent on the yield ofextraction and amount of extracted polyphenols was determined. As solvent water at80 °C was used and mixing time was set to 15 min. The results are shown in Table 2.It can be seen that a higher ratio of solvent results in a higher extraction yield, which is31.96% at a ratio 1/50. At the same ratio the highest amounts of all three analysedpolyphenols were obtained, EC (2.54%), EGCG (5.51%) and ECG (1.89%). Amongthem, the fastest increase was determined for EGCG.

TableTableTableTable 2222:::: Extraction of green tea with different solvents (m(raw material) = 20 g):extraction yield(η), humidity(R) and polyphenol content; Tevap = 40 °C

solventsolventsolventsolventTTTTextextextext

[ °C]

GTGTGTGT////solventsolventsolventsolvent[g/g]

tttt mixmixmixmix

[min]

η η η η

[%]

RRRR

[%]

EC*EC*EC*EC*

[wt %]

EGCG*EGCG*EGCG*EGCG*

[wt %]

EGC*EGC*EGC*EGC*

[wt %]H2O 20 1:10 15 21.18 8.39 2.24 2.14 0.87H2O 40 1:10 15 23.53 8.01 2.30 2.61 1.03H2O 60 1:10 15 22.93 8.82 2.46 3.79 1.35H2O 60 1:10 30 21.17 8.16 2.24 2.69 0.58H2O 60 1:10 60 23.96 8.35 2.13 3.19 0.75H2O 60 1:10 90 22.29 7.36 2.19 3.22 0.79H2O 60 1:10 120 22.16 7.91 2.08 3.18 0.84H2O 80 1:10 15 26.62 8.51 2.32 4.08 1.50H2O 80 1:10 30 24.44 8.56 2.20 4.43 1.57H2O 80 1:10 60 21.95 8.42 2.07 3.49 1.35H2O 80 1:10 90 23.74 9.83 2.08 4.04 1.50H2O 80 1:10 120 24.09 9.11 1.87 3.58 1.41H2O 80 1:25 15 30.22 8.58 2.47 4.50 1.56H2O 80 1:50 15 31.96 9.15 2.54 5.51 1.89MeOH 20 1:10 15 6.51 3.79 2.50 5.02 1.80MeOH 40 1:10 15 12.16 4.18 3.25 6.79 2.59MeOH 60 1:10 15 22.70 4.02 3.09 7.01 2.78EtOH 60 1:10 15 11.41 3.20 0.61 1.03 0.34EtOH 80 1:10 15 15.71 1.66 1.22 2.14 0.77

EtOH/H2O=1:1 80 1:10 15 33.72 8.38 2.32 6.91 2.11

EtOH/H2O=9:1 80 1:10 15 24.24 4.21 2.86 6.56 2.31

*amount if components is calculated on dry basis of material

b) Extraction with water at constant ratio and temperature and different mixing times:Extraction experiments with water as the solvent were performed at 60 °C and 80 °Cand different mixing times, to determine the influence of the temperature and of mixing

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time on the yield of extraction and the amount of extracted catechins. The ratio of rawmaterial and solvent was always the same, 1/10.The results obtained are presented in Table 2. Comparing extraction yields accordingto the obtained mass of extract at both temperatures, it can be seen, that at 80 °C,higher yields then at 60 °C were obtained. At 80°C the highest yield (26.60%) isreached after 15 minutes extraction. At 60 °C, the maximum yield (23.96%) wasobtained after 60 min of mixing. At 60 °C the highest amount of polyphenols wasextracted after 15 min. After 30 minutes, the lowest extracted amount can be seen.Longer extraction times (60 to 120 minutes of mixing) do not effect the amount ofextracted EC, EGCG and ECG significantly at 60 °C. At 80 °C, a slight decrease ofextracted EC and ECG can be observed from 15 to 120 min of extraction. At 60 °C and80 °C, the highest value for extracted polyphenoles was observed for EGCG, followedby EC and ECG.c) Extraction with different solvents at constant ratio 1/10 and constant mixing times

(15 min) and different temperatures:As it can be seen from Table 2, solvent has great influence on the extraction yield andon the amount of extracted polyphenols. The best solvent, according to the highestamounts of polyphenols recovered is methanol: EGCG (7.01%) and EGC (2.78%) at60 °C; and EC (3.25%) at 40 °C. The amount of polyphenols is increasing withincreasing temperature for all solvents. The amount of polyphenols extracted decreasesin the order methanol, water and ethanol at all temperatures.

d) Extraction with different mixtures of water and ethanol at constant ratio andconstant mixing time and temperature:

Extractions with different mixtures of ethanol and water were performed in order todetermine the influence of diluted solvent on the extraction yield and on the amount ofextracted polyphenols. The most epicatechin (2.86%) and epicatechin gallate (2.31%)was obtained with the mixture containing 90% ethanol. The highest amount ofepigallocatechin gallate (6.91%) was extracted with 1:1 mixture of ethanol and water.The lowest amounts of all polyphenols and also the lowest yield of extraction wereobtained when pure ethanol was used. The highest yield of extraction (33.72%) wasachieved with the mixture containing 50% of ethanol, and decreases to 15.71% whenpure ethanol was used as a solvent.Although the best results were obtained with methanol, it is not suitable solventfor powders which are to be used in food industry because of its toxicity. Forthis reason water was chosen as the most suitable solvent for extraction purpose.As it can be seen from results, the highest amount of polyphenols was extractedwith ratio 1/50. For spray process it is better from economic point of view touse lower ratio 1/10, which also gave satisfying results.

3.2.3.2.3.2.3.2. ExtractionExtractionExtractionExtraction andandandand dryingdryingdryingdrying withwithwithwith PGSSPGSSPGSSPGSS dryingdryingdryingdrying processprocessprocessprocessThe green tea extract used for the PGSS drying experiments was obtained by extractionperformed at 80 °C for 15 min by mixing 1 kg of extract in 10 kg of deionised water.

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The experiments were carried out with a Sulzer SMX static mixer comprising fivemixing elements; the diameter of the mixing elements was 6 mm. Two nozzles with 1and 1.4 mm and spray angles of 90 ° from the company Schlick were used.Powders with different polyphenol and caffeine content as well as different watercontent (R) were obtained by changing temperature in the spray tower (Tst), pre-expansion temperature (Tp) and pre-expansion pressure (Pp). Experimental results arepresented in Figure 2. Results are ordered according to the amount of epigallocatechingallate (EGCG), from the highest to the lowest concentration. Main focus of researchwas set on polyphenol obtained during spray process, and in addition caffeine contentin the samples was determined and was found to be between 1.62 and 3.70 wt %The amount of obtained polyphenols (SUM) was the highest in the first experiment(V1) with 8.77 wt % and the lowest in experiment V9, 1.05 wt %.Figure 2a presents the concentration of each of polyphenols obtained in differentexperiments and Figure2b shows the influence of pre-expansion temperature (Tp), andtemperature in the spray tower (Tst) on the amount of obtained polyphenols.Working at extreme conditions (Tp = 145 °C and Tst = 79 °C) during spray process,results in the lowest amount of polyphenols, 1.05 wt % in experiment V9. Very hightemperatures applied; result in degradation of polyphenols, which are thermo sensitivecomponents of tea.

(a) (b)FigureFigureFigureFigure 2222:::: (a) the influence of temperature in the spray tower, Tst and temperaturebefore expansion, Tp on the total amount of obtained polyphenols and (b) the influenceof temperature in the spray tower, Tst on the amount of different polyphenols

In the experiments V7 and V8, the temperature before expansion was reduced to 132and 131 °C. The temperature in spray tower Ts was 61 and 62 °C and the pressure Ppwas set to 98 and 99 bar, respectively. In these experiments the amount of obtainedpolyphenols in the powder was measured with 4.97 wt % and 5.10 wt %. Comparingtemperature in spray tower from V6 (77 °C) and V9 (79 °C), it can be seen that in thisrange it has no effect on degradation.

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In the temperature range from 121 to 125 °C before expansion (Tp), the best qualitypowders were obtained (V1, V4, V11 and V12), with polyphenol content from 8.77 to8.45 wt %.Powders (V2, V5 and V10) with polyphenol content in range from 8.52 to 7.65 wt %were obtained in the temperature range from 110 to 114 °C.Different total amounts of polyphenols in final powders can be explained bydegradation of polyphenols at very high pre-expansion temperature.As it can be seen from Figure 2, temperature in the spray tower, Tst, in the rangebetween 30 and 70 °C, does not influence amount of obtained polyphenols in powders.All values are calculated in g per 100 g of dry raw material.Water content, R in powdered samples is in range from 5.95 to 13.0 %, exception isexperiment V3, where liquid product was obtained, with water content 78.68 %.Water content in powders from experiments V4, V5 and V11, was above 12%, due tothe low temperature in spray tower (below 40 °C).In addition, SEM were taken, to investigate the particle morphology (Figure 3). TheSEM micrographs show spherical particles with an approximate size smaller than 2 µm.It can also be seen that the obtained spheres tend to agglomerate.

FigureFigureFigureFigure 3:3:3:3:Green tea powder and particle morphology of the PGSS samples

4.4.4.4. ConclusionConclusionConclusionConclusionPossible applications for tea catechins in numerous fields continue to grow. Manyexperiments have been performed to show how temperature, solvent, mixing time andof course the drying process influence the quality of the products. The used raw greentea material contains 0.97 g of epicatechin, 3.92 g of epigallocatechin gallate and 1.41g of epicatechin gallate per 100 g of dry raw material. The desired product should havea high value of active ingredients and a water residue as low as possible in order toprevent polyphenol oxidation during storage.This work was separated in two major sections, first optimization of the extractionprocess with the parameters mentioned above; second, optimizing of the drying process.Comparing the results of different solvents, methanol was found to be the best onebecause of good solubility for low-degree polymerization catechins [14]; similar resultswere reported from other authors [11]. After careful consideration of obtained resultsand comparing solvent toxicity, extraction efficiency and percentage polyphenolsobtained, decision to use water as a solvent was made.

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Comparing different temperatures from 20 to 80 °C for conventional extractions withwater, the optimal temperature was found to be 80 °C. Using different ratios of rawmaterial to solvent, ratio m(GT)/m(H2O)=1/50 gave the highest amount ofepigallocatechin gallate (5.51%) after 15 min extraction. At the same time, the highestamount of epicatechin (2.54%) and epicatechin gallate (1.89%) were obtained. Fromthese experiments it can be seen that a higher ratio of water to green tea at the sametemperature and mixing time results in a higher yield of extraction and also the highestamount of extracted polyphenol components.Increasing extraction time does not have such a significant effect on the amount ofpolyphenols extracted. Results were compared for 60 and 80 °C. It can be seen that at60 °C, the polyphenol content in the extract is constant from 60 to 120 minutes ofextraction. On the other hand, at 80 °C, the amount of EC and ECG, starts to decreaseslightly after 15 min of extraction. One of the reasons is the temperature sensitivity ofpolyphenols and the increased oxidation occurring at higher temperature in aqueousphase and possible polymerisation into insoluble compounds..For drying of samples with PGSS drying, water was used as a solvent, with a ratio of1/10 according to the raw material. Extraction time was set to 15 min. A mass ratio1/10 of green tea and water was used. Comparing different conditions applied forPGSS drying process it can be seen, that high pre-expansion temperatures Tp (145 °C)cause degradation of polyphenols (1.05 wt %). Maintaining Tp at approximately 130 °Cand lower, gave satisfying results; the total amount of polyphenols in the obtainedpowders was found to be between 4.97 and 8.77 wt %. Temperature in spray towerranging from 33 to 65 °C has no significant effect on the total amount of polyphenols,but higher temperature results in lower water residue in the sample.

AcknowledgementsAcknowledgementsAcknowledgementsAcknowledgementsThis work has been sponsored by the project “Green/Clean Processing of BioactiveMaterials (SUB CLEAN PROBIOMAT)”, contract Nr. MEST-CT-2004-007767, in theSixth EU Framework Programme (FP6).The authors would like to thank Laboratory for Separation Processes of the Universityof Maribor, Slovenia for analyzing water content in samples; the Adalbert-Raps-Forschungszentrum, Freising, Germany (Technical University of Munich) foranalyzing the samples and their kind help and also NATEX ProzesstechnologieGsmbH for supplying the green tea.

ReferencesReferencesReferencesReferences[1] Y. Hara, Green Tea, Health Benefits and Applications, CRC, New York (2001).[2] T. Yamamoto, L.R. Juneja, D.-C. Chu, M. Kim, Chemistry and Applications ofGreen Tea, 1 ed. CRC Florida 1997.

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[3] C.L Nance, M.P. Williamson, T.G. McCormick, S.M. Paulson, W.T. Shearer,Epigallocatechin Gallate, Green Tea Catechin, Binds to the T Cell Receptor, CD4, J.Allergy Clin. Immun. 117117117117 (2) Suppl. 1 (2006) S325-S325.[4] M. Noguchi, M. Yokoyama, S. Watanabe, M. Uchiyama, Y. Nakao, K. Hara T.Iwasaka, Inhibitory Effect of the Tea Polyphenol, (-)-Epigallocatechin Gallate, onGrowth of Cervical Adenocarcinoma Cell Lines, Cancer Lett. 234234234234 (2) (2006) 135-142.[5] D. Opare Kennedy, A. Kojima, T. Hasuma, Y. Yano, S. Otani, I. Matsui-Yuasa,Growth Inhibitory Effect of Green Tea Extract and (-)-Epigallocatechin in EhrlichAscites Tumor Cells Involves a Cellular Thiol-dependent Activation of Mitogenic-activated Protein Kinases, Chem.-Biol. Interac. 134134134134 (2) (2001) 113-133.[6] H.-K. Park, D.-W. Han, Y.H. Park, J.-C Park, Differential Biological Responses ofGreen Tea Polyphenol in Normal Cells vs. Cancer Cells, Curr. Appl. Phys. 5555 (5) (2005)449-452.[7] O.J. Park, Y.-J. Surh, Chemopreventive Potential of Epigallocatechin Gallate andGenistein: Evidence from Epidemiological and Laboratory Studies, Toxicol. Lett. 150150150150(1) (2004) 43-56.[8] A.G. Paschka, , R. Butler, C.Y.-F. Young, Induction of Apoptosis in ProstateCancer Cell Lines by the Green Tea Component, (-)-epigallocatechin-3-gallate, CancerLett. 130130130130 (1-2) (1998) 1-7.[9] M.Bonoli, M. Pelillo, T. G. Tosch, G. Lercker, Analysis of Green Tea Catechins:Comparative Study Between HPLC and HPCE, Food Chem. 81818181 (4) (2003) 631-638.[10] R. Farhoosh, G.A. Golmovahhed, M.H.H. Khodaparast, Antioxidant Activity ofVarious Extracts of Old Tea Leaves and Black Tea Wastes (Camellia sinensis L.),Food Chem. 100100100100 (1) (2007) 231-236.[11] A. Perva-Uzunalić, M. Škerget, Ž Knez, B. Weinreich, F. Otto, S. Grüner.,Extraction of Active Ingredients from Green Tea (Camellia sinensis): ExtractionEfficiency of Major Catechins and Caffeine, Food Chem. 96969696 (4) (2006) 597-605.[12] A. Yanagida, A. Shoji, Y. Shibusawa, H. Shindo, M. Tagashira, M. Ikeda, Y. Ito,Analytical Separation of Tea Catechins and Food-Related Polyphenols by High-speedCounter-current Chromatography, J. Chromatogr. A 1112111211121112 (1-2) (2006) 195-201.[13] Y. Yoshida, M. Kiso, T. Goto, Efficiency of the Extraction of Catechins fromGreen Tea, Food Chem. 67676767 (4) (1999) 429-433.[14] I.C.W. Arts, P.C.H. Hollman, J. Agric. Food Chem. 46464646 (1998) 5156.

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IIIIzvodzvodzvodzvodEKSTRAKCIJAEKSTRAKCIJAEKSTRAKCIJAEKSTRAKCIJA ZELENOGZELENOGZELENOGZELENOGČČČČAJAAJAAJAAJA IIII SUSUSUSUŠŠŠŠENJEENJEENJEENJE SPREJSPREJSPREJSPREJ PROCESOMPROCESOMPROCESOMPROCESOMPODPODPODPOD VISOKIMVISOKIMVISOKIMVISOKIM PRITISKOMPRITISKOMPRITISKOMPRITISKOMNauNauNauNauččččnininini radradradradDarjaDarjaDarjaDarjaMetercMetercMetercMeterc1111,,,, MarcusMarcusMarcusMarcus PetermannPetermannPetermannPetermann2222,,,, EckhardEckhardEckhardEckhardWeidnerWeidnerWeidnerWeidner11111Katedra za procesnu tehnologiju2Katedra za tehnologiju česticaRuhr Univerzitet, Bochum, Nemačka

Zeleni čaj, u svetu rasprostranjeno osvežavajuće piće, proizvodi se iz nefermentisanihlistova biljke Camellia Sinensis. Uobičajeno, ekstrakcija iz listova se izvodi vodom. Dabi se dobio proizvod u čvstom stanju, neophodno je, naravno, da se ovo vodeniproizvodi suše. Osnovni cilj ovih istraživanje je kako izbeći degradaciju antioksidanatatokom uklanjanja solventa.Ovaj rad je podeljen u dva osnovna dela; u prvom je ispitivan proces ekstrakcije; a udrugom, optimizovanje procesa sušenja.U prvim eksperimentima, ekstrakcija sa različitim solventima (H2O, EtOH i MeOH) narazličitim temperaturama (20, 40, 60 i 80 oC) i sa različitim vremenima (15, 30, 60, 90i 120 min) je izvođena u cilju određivanja optimalnih uslova za dalju preradu. Udaljem radu je korišćen ekstrakt dobijeni vodenom ekstrakcijom na 80 oC za 15 min.U tzv. PGSS (Particles from Gas Saturated Solutions) procesu sušenja, ekstrakt sa do98 mas.% vode je mešan sa pregrejanim CO2 u mikseru u cilju dobijanja homogenesmeše. Smeša je raspršivana mlaznicom u sprej-kolonu pri čemu se obrazuju finekapljice a zagrejani gas dovodi do isparavanja solventa, koji je zajedno sa CO2odvođenventilatorom. Kao rezultat ovog procesa obrazuju se fini prah koji je sakupljan u sprej-koloni. Količina solventa koju je potrebno odstraniti kao i zaostala vlaga u proizvoduveoma zavise od brzine protoka i temperature gasa.Iz dobijenih rezultata može se videti da visoka temperatura pre ekspanzije Tp (145 oC)prouzrokuje degradaciju polifenola (1,05 mass. %). Temperatura od približno 130 oC iniža daje zadovoljavajuće rezultate: ukupna količina polifenola u dobijenom prahu jeizmeđu 4,97 i 8,77 mas. %. Temperatura u sprej-koloni u opsegu od 33 do 65 oC nemaznačajnijeg uticaja na količinu ukupnog polifenola, ali viša temperatura dovodi domanje količine vode zaostale u uzorku.

KljuKljuKljuKljuččččnenenene rererereččččiiii: PGSS sušenje, Ekstrakcija, Zeleni čaj, Antioksidansi