Journal of Tea Science

Analysis of Vitamin B₆ Derivatives in Tea Plant with High Performance Liquid Chromatography

JIANG Shou-hua, ZHANG Jian-yun, HUANG Long-quan

Journal of Tea Science. 2010, 30(2): 79-82. doi:10.13305/j.cnki.jts.2010.02.001

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The determination of Vitamin B₆ (VB₆) derivated in tea plant was described by using high performance liquid chromatography with fluorescence detector. The results indicated that, the contents of VB₆ in tea leaves, tender stem and roots are 3.36 μg/g, 1.27 μg/g and 0.18 μg/g fresh weight, respectively. The constituent ratio of VB₆ derivatives are as follows: pyridoxine 21%, pyridoxal 2.4%, pyridoxamine 19.3%, pyridoxal 5´-phosphate 40.8% and pyridoxamine 5´-phosphate 17.9%. The content of VB₆ in tea leaves increased with maturity of leaf, and decreased with aging of leaf.

Discriminant Classification of Wuyi Yan Tea Based on Multiple Chemical Fingerprint

WANG Li-yuan, CHENG Hao, ZHOU Jian, HE Xiao-yan, XUE Feng-ren, XU Jin-bin, HE Wei

Journal of Tea Science. 2010, 30(2): 83-88. doi:10.13305/j.cnki.jts.2010.02.002

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The method of discriminant classification of Wuyi yan tea based on multiple chemical fingerprint by conjoining two HPLC chromatograms was studied. The results showed that samples from two raw material cultivars or from two districts could be distinguished effectively by using those discriminant method obtained from the investigation. The recognition accuracy for the training sample set was 100%, cross-validating was above 97% and the recognition accuracy for the testing sample set was about 85%. Those result revealed that it was possible to distinguish or verify Wuyi Yan tea by combining the techniques of multiple chemical fingerprint and discriminant classification.

A Fast Analysis to the Content of Reductive Polyphenols in Tea Using Electrooxidation

XU Peng-peng, LI Lin-zi, ZU Yan, MA Wen-xin, LIU Yu-hong, LI Ren-qiang

Journal of Tea Science. 2010, 30(2): 89-94. doi:10.13305/j.cnki.jts.2010.02.003

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For the purpose of obtaining a preliminary quantitative method to analyze the reductive polyphenols in tea that are extremely unstable under normal condition. Reductive polyphenols are related to the antioxidantive activity of tea, and their determination is important for understanding the extent of chemical reaction that occurs in tea during the manufacturing process. Electrooxidation of the reductive polyphenols led to a new absorption maximum at 325 nm. The optical density difference at 325 nm of tea solution before and after electrooxidation was directly proportional to the content of reductive polyphenols, which was used to measure the content of reductive polyphenols in tea. Reproducibility and accuracy of this analytical method was not satisfactory due to the unstable nature of reductive polyphenols under normal condition. Application of this method to the several teas revealed that concentration of reductive polyphenols was high in green tea and very low in Pu-Erh tea.

Ultra High Pressure-assisted Extraction of Fresh Green Tea Infusion

XU Yong-quan, YUAN Hai-bo, WANG Fang, ZHANG Rui-lian, CHEN Jian-xin, YIN Jun-feng

Journal of Tea Science. 2010, 30(2): 95-100. doi:10.13305/j.cnki.jts.2010.02.004

Abstract ( 427 )

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The effect of different ultra high pressure-assisted extraction on the yield, the contents of main chemical components and the sensory quality of fresh green tea infusion was investigated. With increasing of the pressure, the contents of total solids, polyphenols, free amino acids and main catechins components increased, and no significant influence on the colour and aroma quality of fresh green tea infusion observed. There was no significant difference in the contents of main chemical components and the sensory quality when the pressure was between 100 MPa and 300 MPa. However, the sensory quality of the fresh green tea infusion decreased markedly when the pressure reached 500 MPa. After comprehensive comparison, ultra high pressure treatment (100 MPa, 10 min) was the optimum parameter. The cell structure of the tea leaves was damaged after ultra high pressure treated, and the damage degree emphasized with the increasing of the pressure. It may be the reason of why the ultra high pressure-assisted extraction can increase the yield and the content of main chemical components of fresh green tea infusion.

Effect of Different Additives on the Theabrownin and Its Formation Mechanism during Pu-erh Tea Fermentation

GONG Jia-shun, CHEN Yi-jiang, PENG Chun-xiu, ZHOU Hong-jie

Journal of Tea Science. 2010, 30(2): 101-108. doi:10.13305/j.cnki.jts.2010.02.005

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Sun-dried green tea prepared from the fresh leaves of Camellia sinensis var. assamica was used as its starting materials by solid state fermentation. Results showed that the appearance color and soup color value of fermented tea leaves with different treatments showed significant difference. The content of theabrownin in fermented tea leaves in addition of glucose, gallic acid, pyrogallol, pyrocatechol, glycine and mixtures of glucose and gallic acid is 6.99%, 11.29%, 10.22%, 6.31%, 9.25% and 7.30% respectively, and their content is higher than that in dried tea sample (control 1, 1.76%) and fermented sample (2.78%) only added with distilled water (control 2). It is found that there is no significant difference between the samples treated with glucose, gallic acid, pyrogallol, pyrocatechol and glycine as well as administering with potassium sorbate and the control. The results also showed that the ascorbic acid reaction and the components within tea leaves also enhance theabrownin production.

Research on Total Antioxidant Activity of Tea Polyphenols and Other Natural Antioxidants

WANG Yue-fei, XU Ping, LI Lei, ZHANG Xing-hai, SHOU Zhu-zhou, YANG Xian-qiang

Journal of Tea Science. 2010, 30(2): 109-114. doi:10.13305/j.cnki.jts.2010.02.006

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The antioxidant activity of tea polyphenols (TP) and the cooperative antioxidant activity of TP and other natural antioxidants were determined by using ferric reducing /antioxidant power assay(FRAP) established by Benzie and Strain. The results showed that it showed the highest antioxidant activity when the concentration of EGCG in tea catechins was 40%~50%. The cooperative antioxidant activity of antioxidants was related to the antioxidant activity of antioxidants themselves and the effective concentration of antioxidants. A weak activity was showed when the effective concentration of antioxidants was low, and as the concentration increased, the cooperative activity was increasing until the maximum synergizing effect, and then, the synergizing effect on antioxidant activity declined.

Analysis of Aroma Compounds in White Tea Using Headspace Solid-phase Micro-extraction and GC-MS

WANG Li, CAI Liang-sui, LIN Zhi, ZHONG Qiu-sheng, LV Hai-peng, TAN Jun-feng, GUO Li

Journal of Tea Science. 2010, 30(2): 115-123. doi:10.13305/j.cnki.jts.2010.02.007

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The aroma components in Silver Needle Tea and White Peony Tea were extracted by headspace solid-phase micro-extraction (HS-SPME) and analyzed by gas chromatography-mass spectrometry (GC-MS). Results showed that the aroma components in white tea had obvious difference compared with green tea and black tea processed with the same variety of tea leaves. The aromatic components in white tea were mainly alcohols, the content of alcohols in Silver Needle Tea and White Peony Tea reached 70.74% and 60.13% respectively, which was much higher than that in green tea (27.56%) and black tea (45.30%). The content of esters of white tea was higher but the content of aldehydes, ketones and hydrocarbon compounds was lower than those in green tea and black tea. Acids and heterocyclic oxygen compounds were not found in white tea. The major aromatic components in white tea were β-linalool and its oxides, geraniol, methyl salicylate, phenylethyl alcohol and benzyl alcohol, which accounted for 35.70%, 23.47%, 5.87%, 7.06% and 2.02%, of the total aroma extraction of Silver Needle Tea, 35.40%, 11.94%, 10.72%, 6.80% and 2.71% of the total aroma extraction of White Peony Tea respectively.

Study on the Hypolipidemic Effect and Antioxidative Activity of Hubei Qingzhuan Tea

CHEN Yu-qiong, ZHANG Wei, NI De-jiang, CHENG Qian, LIU Xiao-hua, GAN Duo-ping

Journal of Tea Science. 2010, 30(2): 124-128. doi:10.13305/j.cnki.jts.2010.02.008

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The effects of Hubei Qingzhuan tea on hypolipidemic rats were investigated. The results showed, compared with the hyperlipidemia control group, each tested group had significant reduction in the body weight of rats, the serum TC、TG and malondiadehyde(MDA) contents, and marked increase in the level of HDL-C , the activities of SOD and GSH-PX. On the effects of decreasing serum lipids, Qingzhuan tea was more significant than that of Xuzikang—a blood lipid decreasing medicine, and green tea, Qingzhuan tea stored for 10 years was more significant hypolipidemic effect than Qingzhuan tea stored for 1 year. The pathological observation on the liver tissue showed that each tested sample could lighten the denaturation liver cell. We conclude that Qingzhuan tea showed the effect of body weight decreasing, serum lipids decreasing, antioxidation increasing and liver cells protecting of hypolipidemic rats.

Construction and Preliminary Analysis of the Suppression Subtractive Hybridization cDNA Libraries between Dormant and Sprouting Buds of Tea Plant (Camellia sinensis)

WANG Xin-chao, YANG Ya-jun, CHEN Liang, MA Chun-lei, YAO Ming-zhe

Journal of Tea Science. 2010, 30(2): 129-135. doi:10.13305/j.cnki.jts.2010.02.009

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Bud dormancy and its release are important biological phenomena in tea plant (Camellia sinensis). In order to understand the molecular mechanism of tea bud dormancy and its release, 2 SSH-cDNA libraries were constructed using dormant and sprouting buds. The forward library contained genes preferentially expressed in sprouting buds and the reverse library contained genes preferentially expressed in dormant buds. One hundred and ninety two positive clones were randomly selected for sequencing and bioinformatics analyzing from the two libraries. The results showed that differential express genes were enriched effectively in the forward and reverse libraries, and subtraction efficiency reached the demand. Most of the length of inserted fragments was 250~750 bp. It implied that the quality of the SSH-cDNA libraries was satisfied. The bioinformatics analysis results indicated that there were differences between forward and reverse libraries on gene expression profiles. In forward library, the percent of genes related with organelle part and transporter was higher than reverse one. And in the reverse library, the percent of genes related with antioxidant, translation regulator and response to stimulus was higher than the forward. The 2 SSH-cDNA libraries can be further used for gene isolation and provide a foundation for further investigation to explore the molecular mechanism of bud dormancy and its release in tea plant.

Prokaryotic Expression of Polyphenol Oxidase Mature Protein from Camellia sinensis

LIU Jing-wei, HUANG YOU-yi, DING Jian, LIU Cong, XIAO xiu-dan, NI De-jiang

Journal of Tea Science. 2010, 30(2): 136-140. doi:10.13305/j.cnki.jts.2010.02.010

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Camellia sinensis polyphenol oxdiase (PPO) plays essential roles in the quality formation of tea processing. Despite that it always is a hotspot, there is no report on expressing C. sinensis PPO in vitro. Based on purifying the active Yihongzao PPO with transit-peptide expressed in Escherichia coli, the active mature form was also expressed in E. coli and purified from the inclusion bodies. The specific activity of the mature form was higher about three times than that of PPO with transit-peptide, which suggests that the transit-peptide should restrain the activity of PPO in vivo and in vitro. It is helpful to yield and apply for the C. sinensis engineering PPO with high activity in a large-scale.

Analysis of Genetic Diversity and Relationship of Oolong Tea Varieties and Strains Using SSR Markers

DUAN Yun-shang, CHENG Hao, JIANG Yan-hua, WANG Li-yuan, ZENG Jian-ming, LI Xing-hui

Journal of Tea Science. 2010, 30(2): 141-148. doi:10.13305/j.cnki.jts.2010.02.011

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The genetic diversity and relationship of 46 Oolong tea varieties and strains from Guangdong, Fujian and Taiwan were analyzed by 40 pairs of SSR markers. Totally 179 alleles and 329 genotypes were amplified by 40 SSR markers, with the average of 4.48 and 8.23. The average polymorphism information content (PIC) was 0.52.Gene diversity (H), observed heterozygosity (Ho) and genetic diversity were 0.57, 0.40 and 0.59, respectively. Genetic diversity of Oolong tea varieties and stains from Guangdong was higher than that from Fujian and Taiwan. All the tested varieties and strains were clustered according to its geographic source and breeding source using both UPGMA and PCA method. The genetic diversity of tested varieties and strains gained by cross breeding was lower than that of samples bred through other methods. In conclusion, the genetic polymorphism of 46 Oolong tea varieties was relatively abundant and the relationship among them would be of great help to effectively select the breeding parents.

Genetic Diversity and Relationship of Tea Germplasm Resources ‘Huangjincha’ (Camellia sinensis)Revealed by ISSR Markers

NING Jing, LI Jian-quan, DONG Li-juan, YANG Yang, ZHANG Shu-guang, TAN Zheng-chu, ZHONG Xing-gang, ZHU Qi, PENG Ji-guang, HUANG Jian-an

Journal of Tea Science. 2010, 30(2): 149-156. doi:10.13305/j.cnki.jts.2010.02.012

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Genetic diversity and relationship of 110 strains from ‘Huangjincha’ population were analyzed by inter-simple sequence repeat (ISSR) markers. A total of 205 bands were detected by using 18 ISSR primers, of which 187 were polymorphic, and the total percentage of polymorphic bands was 91.22%. Results showed that abundant diversities existed among tea strains studied. The average value of effective number of alleles, Nei’s gene diversity and Shannon’s information index of 110 tea trains were 1.51, 0.30, 0.45 respectively, which indicated that the genetic diversity of ‘Huangjincha’ population was relatively high. The Jaccard similarity coefficient of 110 tea strains ranged from 0.22 to 1.00, and the average value was 0.55. Total of 110 tea strains were divided into seven groups by UPGMA according to the average value of similarity coefficient, and ISSR dendrogram was established, which revealed the genetic relationship between different strains. All the results offer us some supports from molecular level to protect ‘Huangjincha’ population, select fine varieties and crossing parents from them, etc.

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