Journal of Tea Science

Recent Progress in the Research on Fluoride in Tea: Accumulation Characteristics by Plants and Concentrations in Products with Regarding to the Impact on Human Health

RUAN Jian-yun, YANG Ya-jun, MA Li-feng

Journal of Tea Science. 2007, 27(1): 1-7. doi:10.13305/j.cnki.jts.2007.01.001

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This paper reviews recent progress in the studies on i.) Fluoride content in the soils, ii) F concentrations in different tea cultivars, ii) the impact of pH, aluminium and calcium on F absorption by tea plants, iii) F concentrations in marketed made teas as well as iv) the release of F in infusion and risk assessment of F intake by humans from tea drinking.

Advance in the Study on the Chemical Composition and Biological Activity of Pu-erh Tea

LU Hai-peng, GU Ji-ping, LIN Zhi, GUO Li, TAN Jun-feng, PENG Qun-hua

Journal of Tea Science. 2007, 27(1): 8-18. doi:10.13305/j.cnki.jts.2007.01.002

Abstract ( 778 )

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The health function of Pu-erh tea, such as anti-atherogenic、hypolipidemic and anti-obesity effect，has attracted much attention. This paper reviews the chemical composition and biological activity of Pu-erh tea, and discusses the substance basis of biological activty as well as the possible mechanism accordingly.

Effects of the Treatment of Filling Nitrogen in Vacuum and Decaffeinating with Boiling Water on Quality of Green Tea

ZU Feng, CHEN Wen-pin, YU Li-jun, LIU Qin-jin

Journal of Tea Science. 2007, 27(1): 19-26. doi:10.13305/j.cnki.jts.2007.01.003

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This article studied the effects of the treatment of filling nitrogen in vacuum and decaffeinating with boiling water on quality of green tea. Results showed that the two processing technologies could change the constitution of the volatile components significantly, causing a series of change on tea color, aroma, flavor, and constitution of functional components. After filling nitrogen in vacuum singly, the flavor acceptance of tea sample decreased, the comparative content of volatile compound decreased 39%, 27 kinds of detectable volatile compounds and alcohols decreased;the percentage of acid, furan and other volatile compound increased. Compared tea samples after filling nitrogen in vacuum and decaffeinating with boiling water to tea samples after filling nitrogen in vacuum singly, the comparative content of 55 kinds of volatile compounds were decreased, the comparative content of 28 kinds of volatile compounds increased, the total content of volatile compound decreased 56%. The percentage of acid, furan in the tea samples with filling nitrogen in vacuum and decaffeinating with boiling water are lower than those with filling nitrogen in vacuum singly, the flavor acceptance are also improved .These indicated that the process of decaffeinating with boiling water can improve the functional constitution and flavor acceptance of the GABA tea products.

Effects of Different Extraction Processes on the Components of Tea Polysaccharides

ZHOU Xiao-ling, WANG Dong-feng*, LI Su-zhen, ZHOU Xun, HOU Yang-feng, WANG Yuan-hong

Journal of Tea Science. 2007, 27(1): 27-32. doi:10.13305/j.cnki.jts.2007.01.004

Abstract ( 567 )

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Four different treatments including water-extracted process, pectase-extracted process, trypsin-extracted process and combined-enzyme-extracted process were respectively applied to extract tea polysaccharides (TPS) from Laoshan green tea in this article. The extract ratio of combined-enzyme process method reached 5.17±0.17 % and higher than those of the three other process methods. The crude TPS obtained from the four process methods were further purified through Sepharose FF and the main polysaccharides fraction was obtained respectively. Then comparisons on the components of monosaccharides, amino acids in the purified TPS were conducted. The four process methods had no influence on the kinds of monosaccharides in tea polysaccharides, but little on the proportion of the monosaccharisdes. The total sugar content of TPS prepared by the four process methods was decreased in following pectase-extracted process, combined-enzyme-extracted process, trypsin-extracted process, and water-extracted process. Especially, in pectase-extracted process it reached to 95.26±4.09%, while the uronic acids content decreased greatly. The four process methods had no influence on the kinds of amino acids in tea polysaccharides, but great on the proportion of them.

Anticancer Activity of Theaflavin Diagallate and its Mechanism

JIANG He-yuan, Hang Xiao, YUAN Xin-yue, WANG Chuan-pi, Chung S Yang

Journal of Tea Science. 2007, 27(1): 33-38. doi:10.13305/j.cnki.jts.2007.01.005

Abstract ( 459 )

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Theaflavin digallate was purified by Sephadex LH-20 column chromatography. Its anticancer activity and mechanism were analyzed on H1299 and HCT-116 cancer cell lines. Results from MTT assay showed that Theaflavin digallate could inhibit the growth of H1299, and its IC₅₀ value is 25μmol/L. Theaflavin digallate could slightly adjust the cell cycle of HCT-116 cancer cell, and significantly promote the apoptosis of HCT-116 cancer cell at 50μmol/L. Theaflavin digallagte could decrease the expression of cancer-promoting biomarker, Bcl-xL, and increase the expression of cancer-inhibiting biomarker, Bax, on HCT-116 cancer cell line.

A Comparative Study on Bioactivities of Tea Polyphenols and Chlorogenic Acid

ZHANG Xing-hai, WANG Yue-fei

Journal of Tea Science. 2007, 27(1): 39-44. doi:10.13305/j.cnki.jts.2007.01.006

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Objectiveto study the differences of bioactivities of tea polyphenols (TPs) and chlorogenic acid (CHA), methods of POV assay、spectrophotometric determination and MIC were used to compare the antioxidation、scaventing free radicals and antibacterial action of TPs & CHA. Resultsin the six weeks showed that TPs (100βµg/g、200βµg/g) could restrain the POV of lard below 10βmeq/kg, antioxidation rises with concentrations of TPs, as resemble the effect of CHA (81%). On the free radicals, CHA showed selective scaventing ability, IC₅₀(DPPH、·OH) of CHA (81%) is 65βmg/L and 135βmg/L, and CHA (20%) is 327βmg/L and 1β432βmg/L, but TPs is 52βmg/L and 1908βmg/L; In the antibacterial action, TPs and CHA can obviously inhibit both staphylococcus aureus and escherichia coli., The MIC of CHA (81%) is twice as that of CHA (20%) on staphylococcus aureus, 500βμg/g and 1β000βμg/g respectively, that of TPs is 250βμg/g, on escherichia coli.. Conclusion:TPs (95%) exceeds CHA (81%) and CHA (20%) in the antioxidation、scaventing DPPH and antibacterial activity on staphylococcus aureus, but the reverse was in the scaventing ·OH. It was regarded that TPs may play a more important role than CHA in the food and drug.

Preliminary Application of ISSR Markers in the Genetic Relationship Analysis of Tea Plants

LIN Zheng-he, CHEN Rong-bing, CHEN Chang-song, LIN Jin-ke, HAO Zhi-long, GAO Shui-lian, CHEN Lian-cheng

Journal of Tea Science. 2007, 27(1): 45-50. doi:10.13305/j.cnki.jts.2007.01.007

Abstract ( 406 )

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Inter-simple sequence repeat (ISSR) is a kind of effective molecular marker developed on the basis of microsatellite, or simple sequence repeat (SSR). ISSR markers were applied to detect the relationship of the thirty-nine cultivars of tea plants. Fifteen primers, selected from fourty primers, were used to amplify the tea samples one hundred and fourty-three DNA bands were amplified, of which one hundred and thirty-one bands were polymorphic.The percentage of polymorphic bands was 91.6%.By cluster analysis based on ISSR markers using UPGMA,the genetic similarity was from 0.21 to 0.95. The GS was the greatest between Manqilan and Zhuyeqilan, and they had the highest genetic similarity and the smallest genetic distance.The GS between Chongqinpipacha and Yinghong 1 was the smallest and they had the lowest genetic similarity and the greatest genetic difference. Cluster analysis classified the 39 cultivars into 3 major groups (GS=0.20). Chongqinpipacha and Yinghong 1 fell into one group, belong to primitive form Jiulongzhu and Huanglong also fell into one group. The rest formed the third group. The results suggest that ISSR is a useful tool for molecular genetic diversity and relationship analysis of tea cultivars.

Comparative Analysis on Aromatic Components of Green Tea and Fresh Green Tea Beverage Using HS-SPME/GC-MS/GC-Olfactometry/RI Methods

DOU Hong-liang, LI Chun-mei, GU Hai-feng, HAO Ju-fang

Journal of Tea Science. 2007, 27(1): 51-60. doi:10.13305/j.cnki.jts.2007.01.008

Abstract ( 528 )

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：Volatile components of green tea and fresh green tea berverage was extracted using HS-SPME and the major flavor compounds were identified by GC-MS/GC-Olfactometry/RI. The difference of aromatic constituents in composition and relative content between green tea and fresh green tea beverage was also compared.The results showed that the sort、intensity and contribution to total aroma of an aromatic compound could be identified and affirmed effectively by GC-MS/GC-Olfactometry/RI methods; The aromatic constituents of green tea were different from fresh green tea beverage in composition and relative content. Green tea contained 34 kinds of smell compounds, in which 3-Hexen-1-ol, 2-Ethyl-1-hexanol, Benzylalcohol, 1-Octanol, linalool, cis-Linalool oxide, Phenylethyl alcohol, Hexanal, (E)-2-Hexenal, Benzaldehyde, Acetophenone et al were the primary aromatic compounds. Fresh green tea beverage contained 37 kinds of smell compounds, in which linalool, trans-Linalool oxide, Phenylethyl alcohol, Geraniol, Nerol, Nerolidol, (Z)-2-Heptenal, Benzaldehyde, Acetophenone were the essential aromatic constituents.

The Construction of the Engineered Escherichia coli Strain for the Biosynthesis of Theanine

WANG Xian-bo, WANG Li-yuan, CHENG Hao, ZHOU Jian, LIN Zhi

Journal of Tea Science. 2007, 27(1): 61-66. doi:10.13305/j.cnki.jts.2007.01.009

Abstract ( 480 )

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γ-ggt was cloned by PCR from E.coli DH5α. Then, the PCR product of γ-ggt digested with two restriction enzymes, Kpn I and Xho I, was purified and ligated with the pET-32a vector digested with the same enzymes by T4 DNA ligase. Then the ligation product was transformed to E.coli BL21 and the engineered Escherichia coli strain was constructed successfully. The γ-Glutamyltranspeptidase was expressed with induction of 0.05βmmol/L IPTG in 32℃ incubation. The activity of 1βg fresh cells of engineered strain was 2.0βU/g,it is about 15 times higher than that of E.coli DH5α．Under the catalysis of cells of the engineered strain induced with IPTG, the yield of theanine from L-Gln and ethylamine was 29.40βg/L and the conversion rate of L-Gln as to theanine being 48.22%; it is about 100 times higher than that of E.coli DH5α．

Determination of Residual Ethyl Acetate in Green Tea Extract by Headspace Gas Chromatography

HU Hui-lian, DING Nai-li, WU Lian-zhen

Journal of Tea Science. 2007, 27(1): 67-70. doi:10.13305/j.cnki.jts.2007.01.010

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A method for the determination of residual ethyl acetate in green tea extract has been studied by headspace gas chromatography in order to set up an analysis method. A wide bore HP-fast GC residual solvent column was performed, and the effects of the equilibrium temperature and equilibrium time on the determination of ethyl acetate were studied. The results showed that the standard curve was linear in the range of 0.0765~0.612μg/ml (r=0.9993). the relative standard deviation (n=6) of precision was 3.60%. the average recoveries were between 95.42% and 97.88% with RSD in the range of 1.95%~3.09%, the minimum detectable concentration(S/N=3) was 0.005μg/ml. It is a rapid, sensitive, accurate and uncontaminated method and applicable for the determination of residual ethyl acetate in green tea extract.

Effect of Drying Methods on the Aromatic Character of Pu-erh Tea

ZHANG Ling-zhi, CHEN Wei-xin, WANG Deng-liang, ZHOU Li-min, CHEN Yu-fen

Journal of Tea Science. 2007, 27(1): 71-75. doi:10.13305/j.cnki.jts.2007.01.011

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With the aim to study the effect of drying methods on the aroma Characteristics of Pu-erh tea, the headspace solid-phase microextraction (HS-SPME) coupled with capillary gas chromatography-mass spectrometry (GC-MS) was used for the determination of volatiles in Pu-erh tea dried by baking, air-drying and sun-drying respectively. Results showed: Thirty-five compounds representing 95.4% of aroma contents of air-dried sample were identified with lower contents of terpenes and alcohols but higher contents of esters. Some biphenyls compounds which contributed to the stale odor of Pu-erh tea were distinct compounds of the air-dried sample. As for the sun-dried sample, Twenty-eight compounds representing 96.5% of aroma contents were identified with higher contents of ketones and lower contents of esters. In the baked sample, Twenty-four compounds representing 98.6% of aroma contents were identified with more alcohols compounds such as epoxylinalol, α-terpineol, 2-hydroxy-3,5,5-trimethyl-cyclohex- 2-enone contributed to the camerlsed and sweet flower odor of tea. The results were consistent with that of sensory tests. Sensory tests showed: The characteristic aroma of sun-dried tea, baked tea and air-dried tea were pungent, high-fired and stale odour, respectively. Results showed both baking methods and sun-drying methods were not suitable for Pu-erh tea, but the air-drying methods were the best method of the formation of Pu-erh tea aroma.

Influence of Different Enzyme Origin on the Enzyme-Catalysing Synthesizing of Theaflavins in Single and Bi-liquid Phases Systems

GU Ji-ping, LIU Zhong-hua, HUANG Jian-an, SHI Zhao-peng, WANG Gui-xue

Journal of Tea Science. 2007, 27(1): 76-82. doi:10.13305/j.cnki.jts.2007.01.012

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Synthesizing theaflavins (TFs) in single and bi-liquid phase systems was studied by various source of PPOs. The results showed that different effects could be gained in synthesizing the theaflavins by using the various source of PPOs. As to PPO from fresh tea leaves, the effect in bi-liquid phase system was more remarkable than that in single liquid phase system. The content of TFs in ethyl acetate layer in single liquid phase system, amounted at 33.74%, the synthesizing rate of TFs was 14.245%, while in bi-liquid phases system tests, the content of TFs in ethyl acetate layer was 39.74%, and the synthesizing rate of TFs was 31.792%. When the PPO was from pear, the effect in bi-liquid phase was slightly better than that in single liquid phase, the content of TFs in ethyl acetate layer, in single liquid phase system, amounted at 45.73%, the synthesizing rate of TFs was 18.799%, while in bi-liquid phases system, the content of TFs in ethyl acetate layer was 40.20%, and the synthesizing rate of TFs was 22.11%. However, when the PPO from apple, opposite results was gained that the effect in single liquid phase was better than that in bi-liquid phase, the content of TFs in ethyl acetate layer, in single liquid phase system, amounted at 18.22%, the synthesizing rate of TFs was 13.34%, while in bi-liquid phases system, the content of TFs in ethyl acetate layer was 11.56%, and the synthesizing rate of TFs was 6.935%.

Research on the Consumption in Hangzhou Teahouses

ZHANG Ying-bin, GONG Shu-ying, SHI Yan, ZHANG Jian-ying, QIAN Fu-qiang

Journal of Tea Science. 2007, 27(1): 88-93. doi:10.13305/j.cnki.jts.2007.01.014

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Through the questionnaire and statistical analysis, this test gives us a summary to the consumption status in Hangzhou teahouses, including the preferred type and the attractive factors of teahouses, the structure and purpose of consumption, and the content degree. The result showed that the three types of teahouses occupy certain consumption market respectively. Compared with teahouses without buffet dinner, the teahouses with buffet dinner are much more attractive. The consumers prefer the teahouses with wonderful environment, and green tea is the main kind of tea. The major purpose of consumers is forgathering with friends and relaxing. About 20% of consumers think the prize is unreasonable, while nearly 50% think that is reasonable. In a word, most people are contented with the in Hangzhou teahouses.

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