• Journal of the Korean Applied Science and Technology
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• v.30 no.4
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• pp.761-769
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• 2013

This study used HPLC to analyze the contents of catechins, alkaloids, theanine, total phenolic compounds and antioxidant activities of commercial Hadong green tea leaves(Uzen, Sezak, Jungzak, Daezak). The content of catechins, alkaloids, theanine, total phenolic compounds were lower by water extracts than by 80% ethanol-water extracts. Total catechin and alkaloid contents in Uzen(172.33 mg/g, 30.80 mg/g) by 80% ethanol extract were the highest. Theanine contents of 80% ethanol-water extracts ranged form 55.36 to 37.48 mg/g of tea leaves. Total phenloic compounds contents of green tea were higher than Uzen. Antioxidative of green tea by DPPH, FTC, TBA method were higher than that Uzen.

• Food Science and Preservation
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• v.24 no.6
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• pp.871-878
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• 2017

The objective of this study was to compare antioxidant activities of green tea, rosemary, lemon and bamboo leaves extracts using three different extraction methods (80% ethanol sonication extraction, distilled water autoclave extraction, distilled water extraction at room temperature). As a result, green tea and rosemary extracts showed relatively high antioxidant activities compared with those of lemon and bamboo leaves. These green tea and rosemary extracts were subsequently added to soymilk and their mixtures were examined for antioxidant activities. Soymilk added with 10% green tea distilled water autoclave extracts and distilled water at room temperature extracts showed relatively high DPPH, $85.09{\pm}2.26%$, $84.38{\pm}1.97%$, and ABTS radical scavenging activities, $73.43{\pm}2.78%$, $81.34{\pm}4.78%$, respectively. On the other hand, soymilk added with 10% rosemary distilled water autoclave extracts showed remarkably higher DPPH radical scavenging activity while their ABTS radical scavenging ability was similar to that of non-added soymilk. In conclusion, our results suggest that the addition of green tea distilled water autoclave extracts, distilled water at room temperature extracts and rosemary distilled water autoclave extracts to soymilk could contribute to the development of added value soymilk products with increased antioxidant activities.

• Journal of the Korean Society of Food Science and Nutrition
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• v.31 no.5
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• pp.749-753
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• 2002

The effects of green tea powder (GTP) on the rheological properties of dough and gelatinization characteristics were evaluated by farinograph, extensograph, amylograph and DSC. The flours used were high strength flour (HF: 12.5% protein) and blend of 50% high strength flour and 50% low strength flour (HLF: 10.5% protein). As the amount of GTP increased, water absorption, development time and weakness of the dough decreased for both flours, but dough stability increased only for HLF; the extension of the dough decreased but the resistance to extension increased. The pasting temperature increased and maximum viscosity decreased. On the other hand, with the addition of green tea extract to the wheat starch, transition onset temperature, transition peak temper-ature and enthalpy decreased, demonstrating that catechins in green tea facilitate the starch crystal melting.

• Food Science and Preservation
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• v.16 no.2
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• pp.230-237
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• 2009

The phenolic contents, antioxidant effects, and acetylcholinesterase inhibitory activities of hot water extracts prepared from various Korean commercial teas(green tea, puer tea, oolong tea, and black tea) were investigated. Total phenolic contents were in the range 72.03-85.62 mg/g. Flavonol contents of hot water extracts from green tea, puer tea, oolong tea, and black tea were 350.96, 254.17, 334.48, and 240.23 mg/100 g, respectively. Catechin contents were 2,920.35 mg/100 g in green tea, 1,016.23 mg/100 g in puer tea, 2,824.22 mg/100 g in oolong tea, and 1,006.51 mg/100 g in black tea. The highest caffeine content was in the green tea extract. All four extracts scavenged $ABTS^{{\cdot}+}$ radicals in a concentration-dependent manner, and the green tea extract was the most potent in this regard. The highest reducing power was observed in the green tea extract. All four extracts exhibited considerable antioxidative activities in linoleic acid autoxidation, $\beta$-carotene bleaching, and acetylcholinesterase inhibition assays; the effects were concentration-dependent and decreased in the order green tea > oolong tea > puer tea > black tea.

• Environmental Mutagens and Carcinogens
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• v.26 no.3
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• pp.63-68
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• 2006

There are $10{\sim}30%$ polyphenol and $2{\sim}4%$ caffeine in green tea. Caffeine is a kind of alkaloid containing nitrogen which cause stimulation, impatience, headache, insomnia, low birth weight infant. Because of these negative effect, decaffeined beverage came out and decaffeined coffee already have a big market since 1970s. Having proving the physiologic functions of green tea, high consumption of coffee is shifting to green tea. Because of the carcinogenic effect of the organic solvents, decaffeine processing with supercritical carbon dioxide has industrialized and have an advantage in environment-friendly and minimized flavor loss. Decaffeined green tea using supercritical carbon dioxide is considered to be safe but there are not enough study, We investigated the chromosome aberration test with mammalian cell line, CHL. When the cells were treated with 5000, 2000, 1000 ${\mu}g/ml$ and compared with the negative controls, there were no significant (P>0.05) increased chromosome aberration. Same results was observed when adding S9 mixture or not. As a result, water extract of decaffeined green tea using supercritical carbon dioxide does not induce chromosome aberration.

• Environmental Mutagens and Carcinogens
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• v.26 no.4
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• pp.119-124
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• 2006

There are $10{\sim}30%$ polyphenol and $2{\sim}4%$ caffeine in green tea. Caffeine is a kind of alkaloid containing nitrogen which cause stimulation, impatience, headache, insomnia, low birth weight infant. Because of these negative effect, decaffeined beverage came out and decaffeined coffee already have a big market since 1970s. Having proving the physiologic functions of green tea, high consumption of coffee is shifting to green tea. Because of the carcinogenic effect of the organic solvents, decaffeine processing with supercritical carbon dioxide has industrialized and have an advantage in environment-friendly and minimized flavor loss. Decaffeined green tea using supercritical carbon dioxide is considered to be safe but there are not enough study. We investigated the chromosome aberration test with mammalian cell line, CHL. When the cells were treated with 5000, 2000, 1000 ${\mu}g/ml$ and compared with the negative controls, there were no significant(P>0.05) increased chromosome aberration. Same results was observed when adding S9 mixture or not. As a result, water extract of decaffeined green tea using supercritical carbon dioxide does not induce chromosome aberration.

• Mycobiology
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• v.40 no.2
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• pp.124-128
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• 2012

Multiple treatment modalities, including topical and systemic corticosteroid and phototherapy, have been used in treatment of patients with atopic dermatitis. However, long-term corticosteroid therapy may have various adverse effects. The purpose of this study was to investigate the therapeutic efficacy and safety of bath therapy using green tea extracts for treatment of patients with atopic dermatitis. A total of four patients with atopic dermatitis were enrolled in this study. A Malassezia multiplex detection kit was used in performance of multiplex PCR on clinical isolates, which confirmed Malassezia sympodialis. Subjects underwent treatment with bath therapy using green tea extracts three times per wk for a period of 4 wk. Assessment using the scoring atopic dermatitis (SCORAD) index, the visual analogue scale for pruritus, and transepidermal water loss was performed weekly. Laboratory tests were performed before and after treatment. All patients showed marked improvement on the mean SCORAD and visual analogue scale, and a significant decrease in the mean values of serum eosinophil counts was observed after treatment. Bath therapy with green tea extract is an effective, safe, and nonsteroidal therapy for treatment of patients with atopic dermatitis associated with Malassezia sympodialis.

• Food Science and Preservation
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• v.18 no.5
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• pp.643-650
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• 2011

This study was carried out to analyze the quality change of mackerel treated of green tea and lotus leaf boiled water extracts. And investigate the antioxidant effects of them on the lipid peroxidation of mackerel during storage at $4^{\circ}C$ for 28 days. It was estimated periodical measurements of proximate composition, pH, carbonyl, volatile basic nitrogen, trimethylamine-N, acid, peroxide and thiobarbituric acid values. It had no effect on proximate composition compared with non- treated control nearly but, pH of all the samples was increase during 28 days continuously. The contents of volatile basic nitrogen and trimethylamine-N lower than control during storage. Also, acid, peroxide and thiobarbituric acid values of mackerel treated of green tea and lotus leaf boiled water extracts were significantly lower than control throughout storage period. Especially, mackerel treated of 2% green tea and lotus leaf boiled water extracts shows that more effective than 1% of things in antioxidant during storage. Results indicate that the application of green tea and lotus leaf boiled water extract on the surface of mackerel may be useful to lower the rancidity degree and fish odor during storage.

• Korean Journal of Food Science and Technology
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• v.51 no.4
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• pp.356-360
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• 2019

To evaluate antioxidant capacities and total phenolic, flavonoid, and catechin contents of pure green tea packaged in tea bags, green tea bags of 10 commercial brands were purchased and analyzed. Considering commonly used infusion methods, green tea bags were extracted using 150 mL of spring water at $70^{\circ}C$ for 2 min. Ten brands of green tea showed a wide range of total phenolic content (46.3-93.9 mg gallic acid equivalents/g), total flavonoid content (10.3-21.7 mg catechin equivalents/g), and antioxidant capacities (88.8-175.6 mg and 87.9-183.5 mg vitamin C equivalents/g for DPPH and ABTS assays, respectively). Total catechin content of green tea ranged from 33.8-74.7 mg/g, which corresponded to 43.0-108.3 mg/150 mL of cup. Collectively, these results suggest that daily consumption of 3.8-12.5 cups of green tea packaged in tea bags meets the recommended daily intake of catechins in green tea extract as a health functional foods in Korea.

• Journal of Life Science
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• v.21 no.2
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• pp.322-327
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• 2011

The effects of green tea consumption and/or exercise for 12weeks on body weight and select biochemical markers in plasma were evaluated in obese adolescents with a fat ratio of greater than 25%. The subjects were randomly divided into a control group (n=9), green tea consumption group (n=9), exercise group (n=9) and green tea consumption with exercise group (n=9). Subjects in both green tea consumption group and green tea consumption with exercise group were given more than five cups of green tea extract in hot water ($90^{\circ}C$) daily, equivalent to 1.5-1.7 g dry green tea, for 12 weeks. Subjects in both the exercise group and green tea consumption with exercise group participated in a training program (HRmax 60-70%, 60 min/day) for 12 weeks. Control subjects were only given water equal to the quantity of green tea being given to the subjects of green tea consumption. No significant changes body weights were seen in any of these treatments, but the waist to hip ratio was reduced with treatments of both green tea and exercise. The control group showed no significant changes in TNF-$\alpha$, IL-6 and leptin levels. Green tea consumption reduced leptin (p<0.05), TNF-$\alpha$, and leptin levels. Exercise lowered TNF-$\alpha$ (p<0.05), IL-6 (p<0.01), and leptin (p<0.05) concentrations. Meanwhile, a combination of green tea consumption and exercise lowered TNF-$\alpha$, IL-6 (p<0.05) and leptin (p<0.05) levels. These results indicate that green tea consumption and exercise both had a positive effect on the reduction of inflammatory cytokines, TNF-$\alpha$, IL-6 and leptin, in obese adolescents, but no synergistic effect on the reduction of these cytokines.