• Journal of Life Science
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• v.6 no.2
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• pp.104-110
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• 1996

The present study was conducted to elucidate the functional property of tea extract obtained from tea extracts, semi-fermented tea(oolong tea) and fermented tea(black tea). Tea extracts exhibited remarkable nitrite-scavenging actions, and the action increased with the increased of the amount of tea extracts. The nitrite-scavenging actionof tea extracts showed pH dependent, highest at pH 1.2 and lowest at pH6.0. The nitrite-scavenging rate in tea extracts/amine/nitrite systems proved to be faster than that in amine/nitrite systems. To screen the nitrite-scavenging factors, tea extracts were fractionated into water-soluble, methanol-soluble, methanol-precipitate and crude catechin fraction. Among these fractions of tea extracts, the crude catechin fraction possessed greater nitrite-scavenging action than the other fractions. The nitrite-scavenging action of tea extracts increased with the contents of total phenols and an absorbance at 280nm, nitrite-scavenging factors were supposed to be and catechins in tea polyphenol compounds.

• Journal of the East Asian Society of Dietary Life
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• v.21 no.2
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• pp.243-249
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• 2011

This study investigated the physiological and antioxidant activities of green, oolong, and black tea extracts. The crude catechin extract yields of green, oolong, and black tea were 4.9%, 3.4%, and 2.5%, respectively. Total phenol contents of green, oolong, and black tea were 40.9%, 43.0%, and 38.5%, respectively. The order of the electron donating abilities of green, oolong and black tea were green tea>oolong tea>black tea extracts. The SOD-like activities of green, oolong and black tea extracts at 5,000 ppm were 21.2%, 17.5% and 13.9%, respectively. The nitrite-scavenging abilities of green, oolong and black tea extracts were higher than that of ascorbic acid (p<0.05). Antioxidant activities in soybean oil substrates at 500 ppm were in the order of green tea>oolong tea>black tea${\geq}$BHT (200 ppm). Therefore these results showed that the physiological and antioxidant activities of green tea were better than those of oolong and black tea.

• Journal of Life Science
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• v.7 no.4
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• pp.309-315
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• 1997

The fermented black tea with tea fungus (FBTF) was prepared by culturing tea fungus biomass in black tea with 10% sucrose (BT) at 30$\circ$ for 14 days. The flavor quality of FBTF was investigated by sensory and chemical analysis, and the results were compared with BT. The data of sensory analysis indicated that fruity, wine-like, sharp-pungent, and vinegar-like flavor notes were increase, while earthy note was reduced during fermentation. GC-MS analysis of volatile compounds collected from FBTF and BT by Tenax trap showed that linalool, liinalool oxide other flavor compounds known as black tea flavor compounds were disappeared. Some major flavor compounds produced during fermentation were acetic acid, ethanol, limonene, $\alpha$-terpineol, and these volatiles may be attributed to the flavor of characteristic FBTF. Biosynthetic pathway for the formation of limonene and $\alpha$-terpineol are proposed through mevalonic acid pathway using acetic acid as precusor and/or through transformation of linalool and linalool oxide.

• Journal of Food Hygiene and Safety
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• v.31 no.2
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• pp.132-139
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• 2016

The purpose of this study was to investigate the contents of antioxidant compounds and antioxidant activities in teas. A total of 99 teas were tested for their antioxidant activities based on their ability to scavenge DPPH (1,1-diphenyl-2-picrylhydrazyl) free radical. Antioxidant activity was expressed as mg of ascorbic acid equivalents per 100 g tea sample (L-ascorbic acid equivalent antioxidant capacity, AEAC) and was expressed as mg per 1 serving size (free radical scavenging activity, $FSC_{50}$). The total polyphenol contents of the extracts was quantified using the Folin-Ciocalteu method and the total flavonoid contents of the extracts was determined using a modied method of Davis. Vitamin C was analyzed by HPLC method. According to the AEAC value, mate tea, green tea, black tea, oriental raisin tea, chamomile tea and burdock tea showed relatively high antioxidant activities. Polyphenolic compounds were the major naturally occurring antioxidant compounds found in teas and the high concentrations of total polyphenol compounds were observed in black tea, green tea and mate tea. The high concentrations of total flavonoid compounds were observed in mate tea, black tea and yam tea and the amount of vitamin C contents were found to be high in citron tea and green tea. As a result, steeping tea was much higher in antioxidant activity than either powdered tea or liquefied tea. According to the study, a high correlation was demonstrated between the total polyphenol contents and antioxidant activities in teas (r = 0.846) and correlations between the total flavonoid contents and antioxidant activities was statistically significant in teas (r = 0.625). It was found that also the proportional relationship established among the total polyphenol content and antioxidant activities. That is, antioxidant activity of teas has been confirmed to have been caused by the total polyphenol.

• Journal of the korean academy of Pediatric Dentistry
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• v.44 no.4
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• pp.437-445
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• 2017

The aim of this study was to investigate the effects of green tea, black tea, barley tea and roasted corn tea used in South Korea to make tea on the formation of Streptococcus mutans biofilm. The aqueous samples of 4 types of tea were extracted from commercial tea bags using cold water ($7^{\circ}C$) or hot water ($72^{\circ}C$). S. mutans UA 159 was introduced into 96-well plates which contained the tea samples and 1% sucrose media. Crystal violet staining was used to assess the effects of teas on S. mutans biofilm formation. In both groups of green tea and black tea, the biofilm significantly decreased with the solution of $50{\mu}L$ aqueous sample in $200{\mu}L$ media and $100{\mu}L$ aqueous sample in $100{\mu}L$ media (p < 0.05). S. mutans biofilm with $25{\mu}L$ of barley tea or roasted corn tea aqueous sample in hot water ($72^{\circ}C$) for 10 minutes showed significant decrease compared of green tea or black tea (p < 0.05). In this study, green tea and black tea suppress the formation of S. mutans biofilm.

• Korean Journal of Food Science and Technology
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• v.33 no.1
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• pp.12-18
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• 2001

The water-soluble extracts of plants used as tea materials were investigated for their antioxidant activities and active components(total phenolics, ascorbate and selenium). Antioxidant activities of the plant extracts were determined by measuring the changes in both peroxide values(POV method) during storage(36 day, $55^{\circ}C$) and conductivity of soybean oil at $110^{\circ}C$(Rancimat method). Soybean oil without any additive was used as a control. Soybean oil treated with 0.02% BHT was used as a positive control. The test samples were prepared by mixing the plant extracts with soybean oil in 0.02% concentration by weight. The water-soluble extracts of lycii fructus(23 d), oolong tea(23 d), orange peel(23 d), citron(22 d), and apricot(22 d) showed longer induction periods, compared to control(21 d) and BHT(21 d) by POV method. Also water-soluble extracts of oolong tea(12 h), instant coffee(11 h), citron(10 h), cinnamomi cortex(10 h), schizandrae fructus(10 h), lycii fructus(10 h) and apricot(10 h) demonstrated longer induction periods, compared to control(8 h) and BHT(8 h) by Rancimat method. The contents of total phenolic compounds were observed to be high in water-soluble extracts of oolong tea, green tea, black tea, coffee, cinnamomi cortex, and cassiae semen. Ascorbate contents were found to be high in coffee, eucommiae cortex, black tea, ganoderma, cinnamomi cortex, persimmon leaf, chicory, green tea and oolong tea extracts. The selenium contents were not detected in all the extracts. The antioxidative effects of some plant extacts were seemed to be the combined effects of various antioxidant components such as phenolics and ascorbate.

• Journal of the Korean Society of Food Science and Nutrition
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• v.34 no.6
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• pp.869-874
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• 2005

The purpose of this study was to determine the qualities of loaf breads added with green tea powder, minimum fermented tea powder (fermented for 10 hrs), medium fermented tea powder (fermented for 17 hrs), and black tea powder (fermented for 24 hrs). The moisture content of loaf bread added with green tea and three types of fermented tea was $36.02\~36.44\%$ and was similar to the control group of $36.98\%$. The content of crude protein and ash of loaf bread added with green tea powder and fermented tea was higher than that of control group. The water holding capacity of loaf bread added with green tea powder was the highest and was followed by the fermented tea added group and the control group. The volume and specific volume of loaf bread were high in tile order of the control group, the fermented tea added group, the green tea added group. The lightness of loaf bread got lower, while the redness and the yellowness of the bread 9ot higher as loaf bread was added with more fermented tea. The hardness of loaf bread get higher, but the cohesiveness got lower as loaf bread was added with the more fermented tea. The gumminess and chewiness of loaf bread added with black tea powder were the highest. The result of sensory evaluation of the loaf bread showed that the preference of the color was tBle highest in the control group, while the preference of the flavor and the taste was the highest in the green tea group and the minimum fermented tea group. The preference of overall acceptability of loaf bread was the highest in the minimum fermented tea group.

• Journal of the East Asian Society of Dietary Life
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• v.23 no.1
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• pp.44-52
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• 2013

This study investigated hepatic functional improvement and anti-fibrotic effects of water extracts of black tea. Male Sprague-Dawley rats were divided into four groups (normal, control, and two experimental subgroups: Ba, Bb) and observed for 3 weeks. Liver fibrosis in rats developed from carbon tetrachloride ($CCl_4$) administration, except for the normal group. Except for the normal and control group, the two experimental subgroups were fed water extracts of black tea. The food efficiency ratio significantly increased in the experimental group compared to the control group. The experimental group had a significantly lower liver weight compared to the control group. The ratio of liver weight to body weight was significantly lower in the experimental group than the control group. The levels of aspartate aminotransferase, alanine aminotransferase, alkaline phosphatase, blood urea nitrogen, and low-density lipoprotein-cholesterol in serum significantly decreased in the experimental group compared to the control group. The values of hydroxyproline and malondialdehyde in liver were even lower in the experimental group than the control group. In observations on liver histology, weaker inflammation and fibrosis were observed in the experimental group compared to the control group. In conclusion, water extracts of black tea help hepatic cells keep their functions, restraining and protecting the liver from impairments caused by $CCl_4$ administration, and can be effective as anti-fibrotic agents.

• Journal of the East Asian Society of Dietary Life
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• v.11 no.4
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• pp.305-314
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• 2001

The study was conducted to investigate the effect of added green tea and black tea powder on the quality of bread during storage. Tea bread was prepared with 0.1% and 2% concentration of green tea (GT) and black tea(BT) powder. The crude fat contents of GT 2% group and BT 2% group were significantly higher than those of control group. GT l% group and BT l% group. The loaf weight of the control group was the lowest and its loaf volume was the highest. Especially, GT 2% group had the lowest loaf volume. The internal lightness value of control group was the highest. the redness value of BT 2% group and the yellowness value of GT 2% group were the highest. GT 2% group was significantly higher in hardness and gumminess and BT l% group was higher in cohesiveness and springiness. After 5 day storage, the retrogradation of GT 2% group was the highest and that of BT 2% group was the lowest among groups. After 5 day storage. pH. titratable acidity and total colony count of GT 2% group was the lowest and those of control group was the highest. The sensory score of control, GT l% and GT 2% group were evaluated higher than others. The shelf-life of tea breads were prolonged to 1~3 days by adding green tea powder and black tea powder as compared with the control group. but It must be considered the way to increase the quality of bread in loaf volume and retrogradation.

• Journal of Nutrition and Health
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• v.27 no.10
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• pp.1007-1017
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• 1994

In order to investigate the effect of Korean green tea, oolong tea and black tea beverage on the antioxidative detoxification in cadmium(Cd) poisoned rat liver, male Sprague-Dawley rat weighing 143$\pm$3.2g were divided into control and experimental groups. The experimental groups were fed standard diet containing 40ppm Cd and were given distilled water(CD), 5% black tea(BT), oolong tea(OT) and green tea(GT), respectively. Tea beverages were extracted from 5G dry leaves of teas in 100ml hot distilled water by the treatment at 85$^{\circ}C$ for 3 min. Liver xanthine oxidase(XOD) activity was increased by the administration of Cd except GT group. Liver superoxide dismutase(SOD), glutathione peroxidase(GSH-px), glutathione S-transferase(GST) activities were decreased by te administration of Cd but did not decreased by the administration of green tea(in GT group). Vitamin E and reduced glutathione contents were significantly decreased in Cd administered groups. Liver lipid peroxide value in Cd administered groups were increased compared to control group, but was not increased in GT group. Serum glutamic oxaloacetic transaminase(GOT) activities in CD, OT, BT groups were higher than control, but that in GT group was similar to control group. Serum glutamic pyruvic transaminase(GPT) activity was not significantly different among various groups. It was concluded that green tea might alleviate peroxidative damage in Cd-administered rat liver by reinforcing antioxidative detoxification system.