Journal of Tea Science

Influence of Dahongpao Tea Water Extract Feeding at Different Time on Alcohol-induced Acute Liver Injury in Mice

CAO Dan, LIU Zhong-hua, HUANG Jian-an, CAI Shu-xian, WU Xiang-lan, JIN Li-sha, LIN Yong

Journal of Tea Science. 2013, 33(4): 289-294. doi:10.13305/j.cnki.jts.2013.04.013

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In order to compare the effect of Dahongpao tea water extract feeding at different time on alcohol-induced acute liver injury in mice. Fifty mice were randomly divided into five groups and were intragastrically given 60% ethanol (0.01βmL/g) alcohol (alcohol group) or distilled water (normal control). Dahongpao tea water extract was fed at different time, including feeding 2 hours before drinking, feeding while drinking and feeding 2 hours after drinking alcohol. All mice were sacrificed to take serum samples for biochemical measurements, such as glutamic oxalacetic transaminase (AST), glutamic-pyruvic transminase (ALT), total cholesterol (TC), total triglyceride (TG), malondialdehyde (MDA) and total sulfydryl, liver samples for microexamination using HE staining to determine the degree of fatty changes. A mice model of alcohol induced acute liver injury has been successfully established biochemical metabolism index, antioxidant index and microexamination results in mice liver showed that Dahongpao tea water extract fed at different time is able to protect mice from alcohol-induced acute liver injury in different degree. Fed 2 hours before drinking is of best protective effect, and fed while drinking is the second, However, the effect of fed 2 hours after drinking is not significant.

Black Tea Extend the Lifespan of Caenorhabditis elegans Nematode under Oxidative Stress

ZHANG Jian-wei, XIONG Zhe, GAO Yan, PENG Yu-xuan, GONG Yu-shun, LIU Zhong-hua

Journal of Tea Science. 2013, 33(4): 295-300. doi:10.13305/j.cnki.jts.2013.04.002

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The effect of black tea extracts on extending the lifespan of Caenorhabditis elegans nematode under Oxidative stress was studied by the authors. Results showed the mean lifespan was significantly extended upon the concentration of 50βmg/L black tea extract treatment under oxidative stress. Further studies demonstrated that the significant up-regulation of stress-resistance-related enzyme including superoxide dismutase-3 (SOD-3) by 40.8% and GSH-Px by 340.8%,and its up-regulation of stress-resistance-related proteins, including SKN-1::GFP by 10% and DAF-16::GFP by 18%. These results indicate that black tea extracts can extend the lifespan of Caenorhabditis elegans nematode against oxidative stress.

The Antidepressant Effect of Tea Polyphenols to the Chronic Unpredictable Stress induced Depressive Mice

FU Xiao-bin, GOU Ling-shan, HE Dong-mei, JIA Gen-guang, LI Yan, XUE Yun-sheng, LI Sai, LAN Nuo, LIU Yi

Journal of Tea Science. 2013, 33(4): 301-305. doi:10.13305/j.cnki.jts.2013.04.014

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The antidepressant effects of tea polyphenols on the chronic stress-induced depression in mice and the possible underlying mechanism were investigated in this paper. The antidepressant model of chronic unpredictable mild stress mice (CUMS) was established. The activities of the mice exposed to various stress were tested in the open-field, the immobility duration of the forced swimming test and tail suspension test were measured. Meanwhile, the contents of the 5-HT and the NE in the brain tissue were determined, and the activities of superoxide dismutase (SOD), GSH-Px and the content of malondialdehyde (MDA) in the brain tissue were estimated by spectrophotometry. The CUMS-induced depressive mice exhibited significant decrease in the activities in the open-field test as compared with the control group (^#P<0.05, ^△P<0.001), while the immobility duration in the forced swimming test and tail suspension test were significantly increased, and the latency period (^#P<0.05, ^△P<0.001. ^#P<0.05, ^△P<0.05) were shortened. However, tea polyphenols ameliorated the defecits of the behavior of the mice. Moreover, tea polyphenols increased the activities of SOD, GSH-Px, and the content of 5-HT, NE, and decreased the contents of MDA in the brain tissue. The depressive status can be attenuated by the administration of tea polyphenols, the underlying mechanism might be attributed to their antioxidative property and enhancement of serotonergic functions.

Activity Changes in Several Extracellular Enzymes of Eurotium cristatum Fungi During its Growth Period

CHEN Gui-mei, DENG Yong-liang, HUANG Ya-ya, ZHANG Yue, JI Xiao-ming, ZHOU Xing-chang, HU Xin

Journal of Tea Science. 2013, 33(4): 306-310. doi:10.13305/j.cnki.jts.2013.04.003

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In order to explore extra-cellular enzyme secreted by Eurotium cristatum fungi, the enzymatic productivity and activity changes on carboxymethyl cellulase(CMCase), proteinase, amylase, pectinase and lipase were analyzed according to the methods of hydrolyzed circle and liquid cultivation. The results showed that there were obvious hydrolyzed circles appearsed on the plate medium with starch and olive oil, but not on plate medium with sodium carboxymethyl cellulose, pectin and milk. Except lipase, other enzymes were detected and their activities were varied obviously during liquid cultivation.

Research Progress of Cellulase and Pectinase in the Extraction of Tea Leaves

GONG Yu-lei, WEI Chun, WANG Zhi-biao, SHEN Xue-liang

Journal of Tea Science. 2013, 33(4): 311-321. doi:10.13305/j.cnki.jts.2013.04.004

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Tea is one of the most widely consumed soft beverages. Tea beverages more excellent in flavor and formation of less deposits are more preferred. With the development of modern biotechnology, the microbial enzymes are applied in the extraction process of tea leaves. The cell walls of tea leaf and proteins are easy to be hydrolyzed, and the formation of precipitates can be avoided. The extract yields of polyphenols, thearubigins and amino acids were increased. And the tea qualities including color, odour and flavor improved accordingly. In this article, the hydrolytic enzymes including cellulase, pectinase, tannase and protease are introduced in detail, and their applications in tea extraction process are reviewed. The prospects of complex enzymes system in tea extraction process are also previewed.

Determination of Conjugated Caffeine in Tea by Low-pH Precipitation Method

SONG Shuang, HUANG Ye-wei, WANG Xuan-jun, YU Hai-shuang, FANG Chong-ye, SHENG Jun, HAO Shu-mei

Journal of Tea Science. 2013, 33(4): 322-326. doi:10.13305/j.cnki.jts.2013.04.005

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The feasibility and superiority in the determination of conjugated caffeine in tea by the method of low-pH precipitation was investigated in order to provide some theories for the determination of caffeine content in tea accurately. The aqueous extract of green tea, black tea and fermented Pu-erh tea were selected as test samples. The content of conjugated caffeine of the tea samples was determined by the method of low-pH precipitation. Meanwhile, the results of conjugated caffeine content were verified by the method of chloroform-extraction. The results showed as follows: Low-pH precipitation method is suitable for the determination of conjugated caffeine in tea. The content of conjugated caffeine in fermented Pu-erh tea is the highest (2.59%) among the three tea samples. However, the contents of conjugated caffeine in the green tea and black tea were relatively low (0.04% and 0.07% respectively).

The Chemistry and Bioactivity of Thearubigins

LI Da-xiang, WANG Hua, BAI Rui, XIAN Shu, WAN Xiao-chun

Journal of Tea Science. 2013, 33(4): 327-335. doi:10.13305/j.cnki.jts.2013.04.006

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Thearubigins are mixtures of heterogeneous acidic phenolic pigments, which are condensed oligomers or polymers from catechins and theaflavins. Thearubigins contribute to tea color, the body strength, intensity and liquor color of a black tea brew. Due to their heterogeneity, their solubility and chromatographic behaviors are dissilimar and their structures are still ambiguous. The classic isolation method of the thearubigin subfractions has been developed with organic solvent extraction. So far, no thearubigin monomer has been reported. However, some studies have demonstrated that thearubigins possess antioxidative, anti-tumor, anti-mutagenic, anti-carcinogenic, anti-inflammatory, anti-leukemic, obesity-preventive and even anti-neurotoxin activities in vitro and in animal models since 1990s. As the abundant polyphenolic compounds in black tea, thearubigins may be the potential active compounds contributing to human health.

Application Research of Calm-holding Temperature-far Infrared Technology for Green Tea Processing

DENG Yu-liang, YIN Jun-feng, XU Yong-quan, WU Rong-mei, CHEN Gen-sheng, WANG Fang, CHEN Jian-xin, YUAN Hai-bo

Journal of Tea Science. 2013, 33(4): 336-344. doi:10.13305/j.cnki.jts.2013.04.007

Abstract ( 615 )

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By using the response surface design, the technology for raising fragrant processing of the roasted and baked green tea with calm-holding temperature-far infrared technology was been investigated. The results indicated that the optimum parameter of far infrared technology for roasted green tea was upper temperature with 79.2℃, lower temperature with 95.5℃, rotational speed with 351.6βr/min, for baked green tea was upper temperature with 90.8℃, lower temperature with 95.5℃, rotational speed with 335.2βr/min. Compared with the traditional raising fragrant technology, the new process technology is helpful to improve the production efficiency, to reduce the processing cost, and the results on refined aroma, color and luster are excellent.

Green Tea Drying Technology of Low-temperature Vacuum Combined with Hot Air

LIU Yu-fang, LIU Xiao-dong, LIN Guo-xuan, GUO Chun-yu, DENG Li-hong, YANG Chun

Journal of Tea Science. 2013, 33(4): 345-350. doi:10.13305/j.cnki.jts.2013.04.008

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For enhancing the quality of drying green tea, especially guarantee green tea green embellish appearance, the test of following drying process were carried out: using low-temperature vacuum drying combined with hot air to drying green tea after it rolled, take traditional hot air drying and vacuum freeze drying as controls, comprehensive evaluation of the indicators such as chlorophyll, tea-polyphenol, amino acids, effective ingredients preservation degree, green tea sensory quality and energy consumption. The results show that the combined drying technology of green tea got higher score in appearance, aroma and infused leaf than the traditional hot air drying, especially in appearance has obvious advantages in color of dry tea. At the same time, the comprehensive quality is higher than that of frozen vacuum drying process. The energy consumption of combined drying technology lies between hot air drying and freeze vacuum drying.

Effect of Different Processing Technology on the Quality of Black Tea Paste

TAN Chao, LIU Hua-rong, GONG Jia-shun, ZHANG Nai-ming

Journal of Tea Science. 2013, 33(4): 351-357. doi:10.13305/j.cnki.jts.2013.04.009

Abstract ( 554 )

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The tea paste was prepared by using two different pretreatment processes (Conventional extraction, enzyme extraction) and drying methods (boiling water concentration, vacuum concentration), and its major components and active substance were analyzed and sensory quality were conducted. The results showed that the content of total soluble sugar, thearubigin, theaflavin, theabrownin, catechin in tea paste were increased significantly with the method of enzyme treatment and vacuum concentrating technology, and much higher than those tea paste manufactured by other methods. The b/a value and Hab value correlation coefficient in the enzyme treated tea paste is higher. It can better reflect the liquor color and sensory score of black tea paste, and it was regarded that it is suitable to use for black tea paste quality measurement.

Study on Tea Seed Saponin Extraction by Microwave-assisted Method

GONG Zhi-hua, LIANG Dan, ZHANG Zhi-bo, XIAO Wen-Jun

Journal of Tea Science. 2013, 33(4): 358-363. doi:10.13305/j.cnki.jts.2013.04.001

Abstract ( 566 )

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By using tea seed as test material, the effect on ethanol concentration, microwave power, extraction time, solid-liquid ratio and other factors on the extracting yield of tea seed saponin were studied in order to comprehensive exploitation and utilization of tea seed saponins resources, and the optimum technology parameter of microwave assisted extraction of tea seed saponin were obtained. The result showed that extraction parameters of saponin from tea seed by ethanol volume fraction 60%, microwave power 539βW, auxiliary extraction time 7βmin, solid-liquid 1︰50, and the tea saponin yield reached 18.56%, which increased 6.84%, and 6.22% respectively compared to the conventional water extraction method and ethanol extraction method. Besides, the extracting time was shorten signicantly.

Experiment on Mechanical Properties and Crude Fiber of Tea Leaf

LIN Yan-ping, JIN Xin-yi, HAO Zhi-long, YE Nai-xing, HUANG Yi-biao, TANG Hui-ying, CHEN Xin-hua, ZHOU Xiao-yong

Journal of Tea Science. 2013, 33(4): 364-369. doi:10.13305/j.cnki.jts.2013.04.016

Abstract ( 510 )

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The experiment on the crude fiber content and mechanical characteristic of fresh tea leaf showed the elastic modulus of Tie-Guan-Yin、MaoXie、HuangDang、Fudingdabaicha and RouGui is within the range of 4β158.88~14β849.11βkPa, the maximum stess is within the range of 870.00~1β842.97βkPa, the fracture stress is within the range of 673.33~1β639.62βkPa, the influence of leaf position to modulus of elasticity, maximum stess and breaking stress is highly significant. third leaf >second leaf> first leaf. The maximum strain of tea shoots is within the range of 10.61%~18.36%, the fault strain is within 12.19%~26.95%, the leaf position shows a highly significant effects on the maximum stain and breaking strain, and the order as follows: third leaf>second leaf>first leaf, there are some differences between different cultivars.

Effects of Freezing on Quality of Black Tea

ZHANG Yan-fei, LI Li-xiang, ZHANG Xiao-fu, LU Zhao, YU Peng-liang, XUE Chen, HUA Zai-xin, MEI Yu

Journal of Tea Science. 2013, 33(4): 370-376. doi:10.13305/j.cnki.jts.2013.04.010

Abstract ( 567 )

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In order to explore the influence of freezing process on the black tea quality and to improve the quality of black tea, the experiment on the freezing treatment during the processing of black tea was conducted. The results showed that the contents of tea polyphenols, amino acids and other major chemical components were increased in the freezing treatment, but the contents of caffeine and soluble sugar showed a slight reduction. The results of sensory evaluation also showed that the freezing processing products of black tea aroma is pure, with best quality.

Effect of Tea Polyphenols Combined with Citric Acid and Calcium Chloride on the Quality of Dried-seasoned Squid (Dosidicus gigas) during Storage

ZHU Jun-li, SUN Li-xia, DONG Liang-liang, LI Xue-peng, LI Jian-rong

Journal of Tea Science. 2013, 33(4): 377-385. doi:10.13305/j.cnki.jts.2013.04.011

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The effects of 0.15% tea polyphenols (TP) and 0.05% TP combined with 5βmmol/L citric acid and 5βmmol/L calcium chloride dip treatment on the physical, chemical and sensory characteristics of dried-seasoned squid (Dosidicus gigas) during storage at 25℃ was assessed. After the storage, the moisture, crude protein, crude fat, pH and reducing power decreased significantly (P<0.05). The L* value decreased significantly, while C* increased remarkably (P<0.05), which revealed the occurrence of browning reaction in dried-seasoned squid. The progressive degradation of lactose to galactose and glucose, and conversion of TMAO to DMA and formaldehyde were found during the storage (P<0.05), especially in the initial 90βd. The advantages of reducing moisture loss, inhibiting oxidation of lipids, depressing TMAO breakdown and TVB-N accumulation were observed for the TP sample and TP combined with citric acid and calcium chloride sample. Therefore, the addition of TP combined with citric acid could retard quality deterioration of dried-seasoned squid.

Comparison of Chemical Constituents and Antioxidative Activities among Different Grades of Pu-erh Tea

LV Hai-peng, LIN Zhi, ZHANG Yue, LIANG Yue-rong

Journal of Tea Science. 2013, 33(4): 386-395. doi:10.13305/j.cnki.jts.2013.04.012

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The antioxidative activity, aroma constituents and the major chemical components of three grades of Pu-erh tea, i. e. high, medium and low grade, were studied and compared. Results showed that the significant difference（P<0.05）was shown in evaluation of the total antioxidative activity, scavenging hydroxyl free radical activity, scavenging DPPH free radical activity, total amount of alcohols compounds, total amount of heterocyclic oxygen compounds, total flavonoids and tea pigments between high and low grades. When compared with high or low grade, the medium grade of Pu-erh tea was found no significant difference（P>0.05）in the others testing index except the total antioxidative activity, scavenging hydroxyl free radical activity, tea polyphenols and total flavonoids. Principal component analysis showed that the important indicator to distinguish the grade of Pu-erh tea seemed to be the scavenging hydroxyl free radical activity, the total antioxidative activity, tea polyphenols, total flavonoids and total amount of alcohols compounds.

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