Journal of Tea Science

Sensory Characteristics of Tea Polyphenols and It’s Effects on Astringency of Tea

TONG Hua-rong, JIN Xiao-fang, GONG Xue-lian

Journal of Tea Science. 2006, 26(2): 79-86. doi:10.13305/j.cnki.jts.2006.02.001

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There are a large amount of tea polyphenols in tea. Tea polyphenols show great effects on astringency of tea taste. Astringency is the principal sensory notes of tea tastes, and show a great influence on the total sensory quality of tea. This paper reviews the sensory characteristics of tea polyphenols, analysis of astringency and the effects of tea polyphenols on astringency of tea infusions.

Red paleosols and Tea Plant Growth in China

LU Jing-gang, WU Jian-jun, ZHAO Dong, TANG Gen-nian

Journal of Tea Science. 2006, 26(2): 87-90. doi:10.13305/j.cnki.jts.2006.02.002

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This paper tallied up that the distribution of plinthitic red paleosol is just coincide with the tea in the area north of Yantze River(Fig.1).Moreover, there are two tea areas outside of the red earth zone on the distributional map (Rizhao area in Shangdong Province. And Chayu area in Tibet)。It can be recognized that both of them had been influenced by the red paleosol on the soil property. All of these showed that the red paleosol could promote the tea plant growth.Therefore the influences of the red paleosol should not be negnected on the study of tea garden soil.

Mechanism of Polymerization and Structure Characterization of Polyetherified Derivative of Theasaponins

YANG Zhong-ming, ZHANG Ming, DING Zhi, ZHOU Yu-cheng, ZHU Xiao-bing, QI Wei-xin, HU Bing

Journal of Tea Science. 2006, 26(2): 91-95. doi:10.13305/j.cnki.jts.2006.02.003

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The polymerization of theasaponins and propylene oxide catalyzed by double metal cyanide complex was described by the authors. Via ring-opening polymerization, a new polyetherified derivative of theasaponins which has perfect lipophilicity was obtained and the mechanism of polymerization was discussed. The structure of polyether was analyzed and characterized by FTIR and NMR. Results showed that head-tail addition and atactic structure were dominant in polyether microstructure.

Effect of Processing on the Pb and Cu Pollution of Tea

HAN Wen-yan, LIANG Yue-rong, YANG Ya-jun,SHI Yuan-zhi, MA Li-feng, RUAN Jian-yun

Journal of Tea Science. 2006, 26(2): 96-101. doi:10.13305/j.cnki.jts.2006.02.004

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The effect of processing on the Pb and Cu pollution of tea was studied in this paper. Results showed that tea processing was one of the main pollution sources of Pb and Cu. The extent of pollution was varied with the working procedure, machine and its metal composing. Almost every working procedure, including fresh leaves spreading out or withering, deenzyming, rolling or cutting, fermentation and drying could increase the Pb and Cu concentrations of tea. However, rolling and spreading out were the most important procedures resulting in Cu and Pb pollution, respectively. With the increase of rolling pressure and time, the Cu and Pb concentrations steadily increased. Due to different procedures, especially the rolling pressure and time, the Cu and Pb concentrations of made teas were different, oven dried and roast green tea were the highest, followed by CTC (Crushing, Tearing, Curling) and Orthodox black tea, almost no change in Longjing tea processing. The pollution sources were quite different between Cu and Pb. Cu pollution was mainly from rolling machine and the Cu content of the machine. Cu pollution from rolling procedure accounted for 90% of total one. Pb pollution was mainly due to dust, which came from unclean ground and air in the workshop. Therefore, keeping clean in workshop and regulating the metal constitution of rolling machine could reduce the Pb and Cu pollution during tea processing. In addition, clearing the mature leaves and tea dust away after tea primary processing also could decrease the Pb concentration of tea.

Study on Food Functionality of Tea Polysaccharides

LI Lei, WANG Dong-feng, ZHOU Xiao-ling, DING Qing-bo

Journal of Tea Science. 2006, 26(2): 102-107. doi:10.13305/j.cnki.jts.2006.02.005

Abstract ( 504 )

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Two contents of tea polysaccharides, TPSⅠand TPSⅡ,whose content is separately 27.4% and 57.8%, were extracted from tea, and its food functionalities, such as solubility, capacities of oil absorption, moisture absorption and retention, frothing, froth maintenance and apparent viscosity, were investigated. Results showed that TPSⅠ and TPSⅡ could dissolve in water and not in organic solvents of high concentration, and they had capacities of oil absorption, frothing and froth maintenance as well as capacities of moisture absorption and retention in humid and dry environment. With the increasing of content of polysaccharides in TPS, apparent viscosity of TPS increased; and viscosity of TPSⅠ was four times as much as that of TPSⅡ.

Study on Separation and Concentration of Tea Polysaccharides by Membrane System

YIN Jun-feng, YUAN Hai-bo, GU Ji-ping, LIN Zhi-zhong, CHEN Jian-xin, TAN Jun-feng, WANG Fang

Journal of Tea Science. 2006, 26(2): 108-111. doi:10.13305/j.cnki.jts.2006.02.006

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The 50βK membrane has been ascertained as the best membrane for separation and concentration of tea polysaccharides, and on the basis of the result, the treatment had been optimized, and the result showed that contents of total sugar reached 30.37%, and those of tea polysaccharides arrived at 16.89%. In compared with the control, the scavenging rate of ·OH were increased by 39.89%. The experiment showed that tea polysaccharides is separated and concentrated by membrane, and the activity of tea polysaccharides could be remained.

Study on Antioxidative Polyphenol Compounds in Pu’er Tea

LIN Zhi, LU Hai-peng, CUI Wen-rui, SHE Gai-mei, ZHANG Ying-jun, YANG Chong-ren

Journal of Tea Science. 2006, 26(2): 112-116. doi:10.13305/j.cnki.jts.2006.02.007

Abstract ( 484 )

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Eleven phenolic compounds were isolated from the Pu’er tea, which was produced in the post-fermentated process by using the crude green tea prepared from the leaves of Camellia sinensis var. assamica as raw materials. Their structures were identified as gallocatechin(1), (-)-epicatechin(2), (+)-catechin(3), myricetin(4), gallic acid(5), kaempferol(6), kaempferol-3-O-β-D-glucopyranoside(7), kaempferol-3-O-rutinoside(8), quercetin(9), quercetin-3-O-β-D-glucopyranoside(10), 2,5-dihydroxy-benzoic acid(11). This is the first time that compounds 6~11 were found from Pu’er tea. All of isolated compounds were tested for their antioxidative activities by DPPH radical scavenging assay. It was found that compoundsβ2, 3 and 5 showed antioxidative activity close with that of positive control, L-ascorbic acid, and the flavonoids(5, 6 and 9) are more active than the flavonoid glycosides(7, 8 and 10)and compound 11.

Research in Polyphenol Oxidase Activities of Major Oolong Tea Cultivars in Fujian

WANG Li-xia, XIAO Li-xia, LU Zheng, LIN Qi-xun, LU Ze-jian

Journal of Tea Science. 2006, 26(2): 117-121. doi:10.13305/j.cnki.jts.2006.02.008

Abstract ( 500 )

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Crude polyphenol oxidase (PPO) was separately obtained from Maoxie, Tieguanyin, Huangdan, Rougui, and enzymatic properties were examined. The results were as follows: PPO activities increased curvely with the increase of catechol substrate volume if the volume of catechol substrate ranged in 0.3~0.9βml, and decreased when catechol substrate content was greater than 0.9βml, in the reaction system; the enzymatic activities were highest when the ratio of catechol substrate content to PPO content was 1.5:1, the optimum temperature for PPO activities were 45℃、55℃、65℃ respectively, under the condition of 50~90℃ hot water treatment for 1βh, the PPO activities of Maoxie, Tieguanyin, Huangdan, Rougui decreased 34.66%~55.91%, 22.68%~50.89%, 23.14%~53.57%, 31.58%~57.89% respectively, PPO could act under alkaline conditions, the best enzymatic activity was detected under the condition of pH8.6; All the five inhibitors showed some degree of inhibition to PPO activities and the most effective inhibitor was NaHSO₃, next to which was L-cysteine, while the most ineffective inhibitor was NaCl.

Toxicological Research of the Edible Safety of Green Tea Buccal Tablets

SU Mi-ju, WANG Yue-fei, LUO Yao-ping, LI Liang, YANG Xian-qiang

Journal of Tea Science. 2006, 26(2): 122-127. doi:10.13305/j.cnki.jts.2006.02.009

Abstract ( 451 )

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To evaluate the edible safety of green tea buccal tablets(GTBT), tests included acute toxicity test, Aames test, Micronucleus test, Sperm shape abnormality test and thirty days feeding test were performed. Results shows that: The oral maximum tolerated dose(MTD) was higher than 20.0βg／kg·bw both in male or female mice and rats. Ames test, Micronucleus test and Sperm shape abnormality test were positive. No significant toxicity was detected in thirty days feeding test. Conclusion: Green tea buccal tablets has no acute toxicity, no genotoxicity, high in edible safety.

Effects of Tea Polyphenols on the Activity of AngiotensinⅠ Converting Enzyme

ZHANG Bo

Journal of Tea Science. 2006, 26(2): 128-130. doi:10.13305/j.cnki.jts.2006.02.010

Abstract ( 439 )

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Effects of tea plyphenols on angiotensinⅠconverting enzyme（ACE） activity were studied in this paper. Activity of ACE were determined by in vivo and in vitro on rats. The concentrationof polyphenols were 0, 0.31, 0.62, 1.24, 2.48, 4.96βmmol/L in vitro and polyphenols concentrations were 0, 45, 90, 180βmg/kg in vivo. ACE activity decreased markedly with the increase of tea polyphenols level in vivo and in vitro test. Results showed that activity of ACE is inhibited by tea polyphenols in vivo and in vitro test and these results showed that tea polyphenols possess the function of reducing blood pressure possibly.

Study on Optimum Medium for Theanine Biosynthesis in Suspension Cultures of Camellia sinensis

YU Ji-hong, HUA Dong, HUA Ping, LENG He-ping, JIANG Shao-mei, LU Hu

Journal of Tea Science. 2006, 26(2): 131-135. doi:10.13305/j.cnki.jts.2006.02.011

Abstract ( 547 )

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The suspension culture of callus obtained from tender leaves of Camellia sinensis were conducted with MS added to IBA 2βmg/L, 6-BA 4βmg/L and ethyl-amine 25βmmol/L in a fermenter. The effects of different medium composition on the growth of tea cell and the amount of synthesized theanine were analyzed. The orthogonal design was utilized in the experiment. Results showed: both the growth of tea cell and the theanine accumulation reached its peak at19^th~20^th in the whole cultrue cycle. Both growth of the cells and the amount of theanine would present an optimal increment (16.33βg/100βml and 3.357βg/100βml), when the medium mixed with NH₄⁺/NO₃^-1.0/60.0βmmol/L, K⁺100.0βmmol/L, Mg²⁺3.0βmmol/L, H₂PO₄^-3.0βmmol/L, sucrose 30.0βg/L and protein 2.0βg/L. The logarithmic phase and the stationary phase were enhanced and the theanine accumulation was increased, when the amount of protein hydrolysate was raised in the medium. The increasing rate of tea cell growth and theanine accumulation was influenced by the different amount of H₂PO₄^-in the medium. the growth of tea-cell was not significantly effected by both K⁺and sucrose, but it was significantly effected by Mg²⁺. The activity of theanine synthetase（L-glutamate: ethylamine lingase）was significantly effected by NH₄⁺/NO₃^-. The optimal culture-time should be ranged from 19~22 days in a culture cycle.

Determination of Endosulfan and Endosulfan Sulfate in Tea by ELISA

LU Xiao, REN Feng-shan, WANG Wen-bo, DU Hong-xia, LI Hui-dong, DING Rui-yan, ZHU Duan-wei, LEE Nanju A, SHEILD Ross, KENNEDY Ivan R

Journal of Tea Science. 2006, 26(2): 141-146. doi:10.13305/j.cnki.jts.2006.02.013

Abstract ( 437 )

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A rapid method based on Enzyme-linked immunosorbent assay (ELISA) was developed for determination of endosulfan isomers and endosulfan sulfate in commercial black and green tea. The average recoveries obtained from crude extracts ranged from 86.6% to 91.1%, which from purified extracts ranged from 68.7% to 123%. The liner range of the standard curve was from 1βµg/L to 10βµg/L. The detection limit of crude extract was 2βmg/kg and the purified was 0.06βmg/kg. This study showed a validation of endosulfan analyzed in tea by ELISA and GC-MS at different levels and proved that ELISA is a quick, low cost and practical technique for monitoring pesticides in tea.

Analysis of Theaflavins by Capillary Electrophoresis

XIA Wen-juan, ZHANG Li-xia, SHI Zuo-an, JIA Ming

Journal of Tea Science. 2006, 26(2): 147-153. doi:10.13305/j.cnki.jts.2006.02.014

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The investigation optimum analytical conditions in the determination of theaflavins(TFs) with capillary electrophoresis was described. The electrolyte solution was consisted of 250βmmol/L H₃BO₄, 10βmmol/L KH₂PO₄, 0.75βmmol/L SDS and 20% (v/v) acetonitrile under pH7.5. The work parameters of the instrument were selected as follows: voltage 25βkV, column temperature 20℃, and detecting wavelength 200βnm. By using this method, the four majors of TF could be separated each other completely within 10 minutes and each had a good linear relationship between its peak area and corresponding concentration (r=0.9945~0.9990). The minimum concentration limit was between 0.53~0.64βμg/ml. The mean recoveries of TFs monomers varied from 92.50% to 108.36%. The coefficients of variation were less than 2.67%. Results showed that the method was simple, rapid and accurate for TFs to be determined in black tea and TFs products.

Studies on a Continuous Tea Roasting Multifunction Machine and its Mechanizing Technology

PAN Zhou-guang, HU Jin-hua

Journal of Tea Science. 2006, 26(2): 154-158. doi:10.13305/j.cnki.jts.2006.02.015

Abstract ( 397 )

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The continuous tea roasting multifunction machine, which is designed by the authors, is consisted of thermostat, pressure control device, auto-transport device and mechanical device including pans. It characterized as small volume, light weight, simple structure, convenience manipulation and tending to pipelining. This article pays more attention to the mechanizing technology in the manufacture of flat-type tea was investigated. Results showed that the quality of Longjing tea processed by the continuous tea roasting multifunction machine is better than that of processed by hand. Thus it is a high efficient machine with developmental potential and can be applied in both large scale manufactories and small workshop.

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