Journal of Tea Science

Present Studies and Research Prospects on the Methylated EGCG

WU Yan-jun, WANG Xiao-gang, WAN Xiao-chun

Journal of Tea Science. 2010, 30(6): 407-413. doi:10.13305/j.cnki.jts.2010.06.001

Abstract ( 377 )

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EGCG3"Me was first isolated from green tea in 1982, and its potential antiallergic activity was reported. In recent years, some other methylated EGCG were discovered in tea or vivo metabolites. The isolation, function and synthesis of methylated EGCG were reviewed in this paper. The separation methods of methylated EGCG including Sephadex LH-20 chromatography, high-speed countercurrent chromatography, Toyopearl HW-40S medium-pressure chromatography, and preparative high performance liquid chromatography(pHPLC) were summarized. Compared to the biological activities of EGCG, the methylated form showed the higher activities in anti-allergy, anti-cytotoxin, lipoxygenase inhibition and inducible nitric oxide synthase(iNOS) inhibition, and liver cells protection. The synthesis of methylated EGCG include chemical synthesis and biosynthesis.

Molecular Targets for Cancer Chemoprevention by (-)-Epigallocatechin Gallate of Green Tea

GU Cheng-bo, YUAN Xiao-han, FU Yu-jie, ZU Yuan-gang, ZHAO En-ze, LI Wang, WANG Qiu-xue

Journal of Tea Science. 2010, 30(6): 414-422. doi:10.13305/j.cnki.jts.2010.06.002

Abstract ( 309 )

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(-)-Epigallocatechin gallate (EGCG) is the most active and major polyphenolic compound in green tea. The molecular mechanisms and targets on the action of EGCG have been extensively investigated. This paper reviewed some of the reported mechanisms and possible targets for the action of EGCG, and strategies for cancer chemoprevention by EGCG in clinical trials were discussed. It provides a new inspiration for cancer chemoprevention.

Study on the Chemical Component of E8 Fraction from Pu-erh Tea

LU Hai-peng, LIN Zhi, ZHONG Qiu-sheng, WANG Li

Journal of Tea Science. 2010, 30(6): 423-428. doi:10.13305/j.cnki.jts.2010.06.003

Abstract ( 352 )

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The chemical components of E8 fraction of ethyl acetate extract from Pu-erh tea was analyzed by HPLC preparative chromatography and its chemical structure was also identified by LC-MS and NMR. Results showed that five compounds were identified as follows: 3',4',5-Trihydroxy-7-Methoxyflavone, 3',4',5,7-Tetrahydroxyflavone (Luteolin), Quercetin-3-O-β-D-glucopyranoside, 3',4',7-Trihydroxy-5-methoxyflavone-7-O-β-D-glucopyranoside and 3',4',7-Trihydroxy-5-Methoxyflavone.

Study on the Change of Main Microbial Population and Enzyme Activity in Post-fermented Process of Guangdong Crusted Tea

CHEN Dong, LI Jing-jing, FANG Xiang, HUANG Guo-zi, QIAO Xiao-yan, WU Hua-ling, LAI Zhao-xiang

Journal of Tea Science. 2010, 30(6): 429-434. doi:10.13305/j.cnki.jts.2010.06.004

Abstract ( 340 )

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Treated Lingtou Dancong as materials to make crusted tea. The change of microbial population, biochemical composition and dominant enzymes were researched at the different stages in the post-fermented process. The results showed that the Penicillium chrysogenum and Aspergillus were the main microbial population. The contend of biochemical composition related to tea quality were decreased, such as tea polyphenols, theaflavins, thearubigins and free amino acids , while caffeine and theabrown were increased. The bioactivity of Pectinase and cellulase reached to the peak at the third stage. Polyphenol oxidase activity was low in the whole process.

Determination of Monosaccharides and Disaccharides in Tea by High Performance Liquid Chromatography- Evaporative Light Scattering Detector

YUAN Yong, HUANG Jian-an, LI Yin-hua, CHEN Jin-hua, YUAN Ling, LIU Zhong-hua

Journal of Tea Science. 2010, 30(6): 435-439. doi:10.13305/j.cnki.jts.2010.06.005

Abstract ( 353 )

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A method for determination of monosaccharide and disaccharide in tea by HPLC-ELSD was developed. Shodex NH₂P-50-4E (4.6 mm×250 mm, 5 μm) column was used at 20℃, acetonitrile and water used as mobile phase, for gradient elusion with the flow rate of 1.0 mL/min. The ratio of organic solvent was controlled by a gradient elution procedure. The procedure was as follows: 85% acetonitrile in 0~14 min, 70%~80% acetonitrile 14~16 min, 70% acetonitrile 16~28 min, then 70%~80% acetonitrile 28~32 min. At last, the ratio of acetonitrile increased to 85%. With the use of evaporative light-scattering detector, the nebulization chamber temperature was 30℃, the drift tube temperature was 70℃ and nitrogen pressure was 310.275 Pa. The calibration curves of rhamnose, arabinose, xylose, fructose, mannose, glucose, sucrose and maltose showed good linearity in the range of 3.202~184.828 μg. The recoveries of fortified 8 kinds of sugar were 90.97%~105.07%, limit of detention was 6.976~1 376.297 ng. Results indicated that the method was simple, rapid and could effectively separate the target component.

Determination of Water Content of Tea by Low Field Nuclear Magnetic Resonance Technology

LI Ran, CHEN Shan-shan, YU Jie, YANG Lei, WANG Hong-zhi, ZHANG Xue-long

Journal of Tea Science. 2010, 30(6): 440-444. doi:10.13305/j.cnki.jts.2010.06.006

Abstract ( 461 )

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Research on the determination of water content of tea by using low field NMR instrument has been conducted. The purpose is to develop a more rapid, accurate and nondestructive method to measure the water content of tea. In this experiment, six pure water samples with different weights were prepared as standard samples to test their FID signals. FID signal data were fitted to a line equation. Five tea samples were prepared to test their FID signals and calculate the water content of tea by the fitting equation, then compare the results with national standard method. Result showed that the determination of water content of tea by low field NMR could obtain a more rapid and accurate result. The result by low field NMR is about 1% higher than that of the national standard method, because the drying method can’t dry the bound water completely,but the NMR measures both the content of free water and bound water.

Determination of Main Free Amino Acids in Tea by Gas Chromatography-Mass Spectrometry (GC-MS) and Gas Chromatography-Flame Ionization Detector (GC-FID)

ZHANG Jia, WANG Chuan-pi, RUAN Jian-yun

Journal of Tea Science. 2010, 30(6): 445-452. doi:10.13305/j.cnki.jts.2010.06.007

Abstract ( 552 )

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Free amino acids are important metabolites and contributors in green tea quality. Methods were developed to quantitatively analyze free amino acids in particular theanine in tea by Gas Chromatography/Mass Spectrometry (GC-MS) and Gas Chromatography/Flame Ionization Detector (GC-FID). The derivative reagent used in this study was N-tertbutyldimethylsily-N-methytrifluroacetamide (MTBSTFA, ≥95%) with tert- butyldimethylsilyl chloride (TBDMSCl, 1%). Conditions for derivatization (reagent, temperature, time, and acidity) were optimized to give high efficiency. The optimized procedure was as follows: dried amino acids standards or tea extract (water) under N₂ gas were re-dissolved in acetonitrile (ACN) and derivatized with MTBSTFA (1:1 to ACN) at 110℃ for 30 min. Analysis of pure amino acid standards showed good linearity (R²≥0.99) within the ranges of 10 to 1 000 nmol. Three peaks were detected for theanine. The MS data indicated that only the third peak (according to peak times) was the completely derivatized product while the first was cyclic and the second was a product of one N-end non-derivatization. Free amino acids in tea sample were quantified by the developed methods and the results were comparable to those analyzed by Amino Acids Autoanalyzer. Recoveries of theanine, alanine, serine, aspartate, glutamate, and glutamine were 85%~108% ranges for spiked tea extract. The developed GC-MS method provided a potential methodology to investigate nitrogen and theanine metabolism in tea plants by quantifying the abundance of ¹⁵N labeled amino acids.

Shape Extraction and Varietial Discrimination of Tea Based on Digital Image

LU Jiang-feng, SHAN Chun-fang, HONG Xiao-long, QIU Zheng-jun

Journal of Tea Science. 2010, 30(6): 453-457. doi:10.13305/j.cnki.jts.2010.06.008

Abstract ( 450 )

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The key methods of tea image processing were studied, including threshold transforming, median filter, image mark and boundary following. These methods solved the problem of how to accurately extract and calculate the characteristic parameters of tea shape. The software for tea quality detection based on digital image was developed. The functions, such as collection of tea image, image processing and extraction of characteristic parameter, could be accomplished. Using the software, 17 shape characteristic parameters were collected from 108 pieces of three different kinds of tea. And 6 characteristic parameters were used to build the back propagation-artificial neural network (BP-ANN) model. The variety from thirty unknown samples were predicted by this model and the recognition rate of eighty percent was achieved.

Effects of Green Tea Powder and Tea Polyphenols Supplemented with Basal Diet on Lipid Metabolism of Roman Layers

SHAO Lei, ZHUO Yi-bin, WAN Xiao-chun, HU Jing-wei, CHEN Wei, SHANG Yan-yan

Journal of Tea Science. 2010, 30(6): 458-464. doi:10.13305/j.cnki.jts.2010.06.009

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The 18-week old roman layers were applied in this investigation. 1620 roman layers were randomly distributed to nine groups, each group includes three replications and each replication has sixty chickens. The total period lasted for 98 days. Control group was fed basal diet,the other eight groups received respectively diets with the addition of 2, 4, 6, 8 g/kg green tea powder (GTP) and 0.5, 1.0, 1.5, 2.0 g/kg tea polyphenols (TPs). The aim of this study was to investigate the effects of GTP and TPs on total cholesterol (TC) and total triglyceride (TG) levels of leg muscle, pectoral muscle, egg and blood of roman layers. To determine the samples on a regular basis, the results showed that the addition of 6 g/kg,8 g/kg GTP, 1.5 g/kg and 2.0 g/kg TPs into diets can reduce TC and TG level in organism, egg and blood, the largest trend of reduction occurred from eight to ten weeks. The effect of TPs was better than that of GTP. This research would provide the groundwork for the development of GTP applied in chicken feed.

Influence of Tea Solution on Electrophysiological Character of Toad’s Sciatic Nerves

ZHAO Yi-liang, WANG Min, AI Hong-bin

Journal of Tea Science. 2010, 30(6): 465-469. doi:10.13305/j.cnki.jts.2010.06.010

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In order to probe the influence of the different concentration of tea solution on the electrophysiological character of toad’s sciatic nerves, the toad’s sciatic nerves were immersed in different groups of solution respectively: normal Ringer’s solution and different concentration of tea solution. After the different intervals of immersion time, the width, the amplitude, threshold intensity, refractory period, conduction velocity of the action potentials of the sciatic nerves from each group were measured respectively. The results showed that the lower concentrations of tea solution increased the amplitude and the conduction velocity of the action potential; but the width, threshold intensity and the refractory period of the action potential of the sciatic nerves were decreased. The case was reversed when the solution concentration was raised and the interval was prolonged. This can be concluded that the excitability of nerves could be increased by the lower concentration of tea solution, but it could be decreased as the solution concentration was raised and the interval was prolonged.

Effects of Pu-erh Tea on Hyperlipidemia, Antioxidation and Vascular Endothelium Protection in SD Rats

XU Xiang-ting, WANG Peng, LUO Shao-zhong, HOU Yan, YANG Ji-hong, SHAO Wan-fang

Journal of Tea Science. 2010, 30(6): 470-474. doi:10.13305/j.cnki.jts.2010.06.011

Abstract ( 409 )

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To explore the effects and mechanisms of Pu-erh tea on hyperlipidemia treatment, antioxidation, vascular endothelium protection and artherosclerosis prevention. Hyperlipidemia were successfully induced in SD rats. Different doses of Pu-erh tea were administered to these rats for 35 days started from the 28th day of induction. Body weights of all animals were recorded during experiment. At the experimental endpoint, blood lipid levels and plasma NO levels were measured. Moreover, aortas of rats were collected to examine patho-histological changes. Results: The comparison on fermenting and fermented Pu-erh tea groups and model group revealed that: (1) Bodyweights were reduced remarkably in Pu-erh tea groups. (2) Levels of TC, TG and LDL-C were decreased and NO content increased significantly in Pu-erh tea groups. (3) Endothelial cells damage was reduced as well as the level of ET-1 in vein. Conclusions: (1) Pu-erh tea can be used as treatment for hyperlipidemia induced by high lipid diet, fermented Pu-erh tea shows a stronger lipid down regulating effect than fermenting Pu-erh tea. (2) Pu-erh tea can protect vascular endothelial cells, and this effect may be associated with increasing plasm levels of NO, and decreasing of ET-1.

Antioxidtive Activities of Pu-erh Tea Extracts and Their Protective Effect on HUVEC Damage Induced by Na₂S₂O₃

WANG Yue-fei, LUO Zi-hua, WU Xin-rong, CHEN Hong-bo, XU Ping, YANG Xian-qiang

Journal of Tea Science. 2010, 30(6): 475-481. doi:10.13305/j.cnki.jts.2010.06.012

Abstract ( 322 )

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Extracts of raw and ripe Pu-erh tea were prepared from tea dust during processing. The antioxidtive activities of extracts were evaluated by ABTS and FRAP systems. The potentially protective effects of extracts on human umbilical vascular endothelial cells(HUVEC) were investigated in Na₂S₂O₃-induction model. The results showed that the extract of raw Pu-erh tea had stronger antioxidtive activity than that of ripe Pu-erh tea in both test systems. But extract of ripe Pu-erh tea showed a less protective effect than that of extract of raw Pu-erh tea on the HUVEC cell damage induced by Na₂S₂O₃, and relevent with tea polyphenols under certain concentrations.

The Emprical Analysis of Tea Consumption in the Rural Areas in Guangdong

ZHANG Yu-xiong, TANG Yue-yue

Journal of Tea Science. 2010, 30(6): 482-488. doi:10.13305/j.cnki.jts.2010.06.013

Abstract ( 412 )

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This paper surveyed the tea consumption in the rural areas in Guangdong, including favorite beverage, average consumed tea quantities in each day, be loved tea sorts, the most caring factors in selecting tea, the tea prices, the chosen causes of drinking tea, the motive of going to tea house, the opinions on tea etiquette, the most profound impression on performance of tea ceremony, the character of tea itself, the most cared factors on tasting tea, the environment in appreciating tea and the choice of packing styles of different kinds of tea. The research indicated that the folk tea consumption has a deep foundation supported by folk tea culture. The tea enterprises are recommended to pay close attention on the current situation and change of folk tea culture in the process of the production, sale and relevant service. The relevant government departments are recommended to survey, sort, and tap the folk tea culture such as folk tea custom, so to promote the economy of tea industry and folk culture to achieve common prosperity and harmonious development.

Study on the Skills of Giving Tea, Tea Competition and Jian Kiln Black Glazed Ceramic Tea-Calices in Song Dynasty

HU Xiao-jun

Journal of Tea Science. 2010, 30(6): 489-492. doi:10.13305/j.cnki.jts.2010.06.014

Abstract ( 461 )

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In Song Dynasty, tea set represented by Song Jian kiln and the appreciation standard of white bubble of tea infusion considered as top grade, were the aesthetic consensus in cultural life. The emergence of Jian kilns, witnessed the culture transition of tea art from Tang Dynasty to Song Dynasty, and the unique drinking skills can also be found in the artifacts. In this paper, the reason of rise and decline of black glazed ceramic in Jian kiln, as a reference for exquisite aesthetic sense, lifestyle, and cultural phenomena with “Song-style”, was revealed by investgation on the relationship between giving tea, skills of tea competition in Song Dynasty and tea-calices black glazed ceramic in Jian kiln.

Comparation on the Development of Coffee, Cocoa and Tea of the World

ZHU Yong-xing, JIANG Ai-qin

Journal of Tea Science. 2010, 30(6): 493-500. doi:10.13305/j.cnki.jts.2010.06.015

Abstract ( 515 )

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The reletive data of coffee, cocoa and tea since 1961 were collected and coordinated. With these data the statistic analysis on the cultivated area, yearly output, per unit yield, export amount and their prices were carried out. Based on these analysis the developing course and character of these three soft beverage cropes were discussed respectively, and further the interaction amoung these three crops and their further developing trends were also involved.

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