• Korean Journal of Food Science and Technology
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• v.40 no.5
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• pp.485-490
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• 2008

In this study, organic tea leaves were characterized with the aim of developing an organic beverage process. The green tea leaves grown using organic farming techniques were collected in Haenam, Korea. Catechins in green tea leaves were extracted by chloroform and ethyl acetate and these were then analyzed quantitatively and qualitatively by HPLC (high pressure liquid chromatography). The color and pH values of the green tea extracts were also measured. The catechin levels of April-harvested, May-harvested and June-harvested, semi-fermented leaves at 0.5% were 66.24, 29.19, 57.11, and 5.27 ${\mu}g/mL$, respectively. Among the detected catechins, the level of (-)-epigallocatechin gallate was the highest while that of (-)-epigallocatechin was not detected. The June-harvested leaves were selected as raw material for development of the green tea beverage, based on the levels of catechins, economic viability and yield of tea extract. As the level of extract increased, the levels of catechins of 0.1, 0.2, 0.5% also increased by 1.5, 11.78 and 41.01 times. From the results of the sensory evaluation of June-harvested leaf-extract, the sensory score of color was the highest in 0.1%, while the flavor and overall quality were the highest in 0.2%.

• Journal of Life Science
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• v.17 no.8 s.88
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• pp.1111-1114
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• 2007

The volatile flavor components of buckwheat (Fagopyrum esculentum Moench)-green tea were analyzed and identified. To make tea having good flavor and functional property, parched buckwheat (50%) was mixed with green tea (50%). The extraction of volatile flavor compounds of buckwheat-green tea was accomplished by a simultaneous distillation and extraction method using a Likens and Nickerson's extraction apparatus. The concentrated extract was analyzed and identified by gas chromatography and GC-mass spectrometry. The main volatile flavor components of buckwheat-green tea were compounds that originated from parched buckwheat and the green tea. The former were 15 pyrazines having roasted and nutty aroma and methylbutanals and furfural having sweet-aroma. The latter were nerolidol, linalool, indole, ${\beta}-ionone$ and geraniol etc having flower-like odor in green tea.

• Textile Coloration and Finishing
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• v.20 no.5
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• pp.7-13
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• 2008

In order to introduce new functions onto textile fabrics, nylon and cotton were treated with green tea extracts. And then the anti-oxidant activity of fabrics treated with the extracts was evaluated by Blois method using DPPH ($\alpha$, $\alpha$-diphenyl- $\beta$-picrylhydrazyl). The anti-oxidant activity was exhibited on the textile fabrics treated as well as by the extracts itself. The cotton fabric treated with 10% o.w.f. of extract appeared to have almost 90% of anti-oxidant activity and 95% was obtained for nylon.

• Journal of Nutrition and Health
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• v.28 no.1
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• pp.15-22
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• 1995

The antioxidant effects of aqueous green tea extracts with $\alpha$-tocopherol and lecithin dissolved in lard were investigated on the lipid metabolism in serum and liver of Sprague-Dawley male rats. Elderly male rats were fed for 8 weeks by different experimental diets containing 10% lard(w/w), 0.5% aqueous green tea extracts, 0.05% $\alpha$-tocopherol and 1.0% lecithin. By the addition of the mixture of the antioxidants, the level of total cholesterol. HDL-cholesterol and triglyceride in serum and liver were not changed. The activities of glutathione peroxidase were significantly increased in the case of addition of the antioxdant mixtures but the activities of superoxide dismutase and glutathione S-transferase were not affected.

• Korean journal of food and cookery science
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• v.27 no.5
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• pp.567-575
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• 2011

This study was investigated the antioxidative and antimicrobial activities of a water extract (70$^{\circ}C$) of traditional Korean teas (rose, chrysanthemum, pine needles, mulberry, persimmon leaves, and green tea). Total phenol contents in rose, chrysanthemum, pine needles, mulberry, persimmon leaves, and green tea were 272.8, 74.6, 153.5, 73.5, 69.5, and 260.8 mg tannic acid/g extract, respectively, whereas total flavonoid contents were 75.1, 47.8, 26.8, 40.0, 27.9, and 99.5 mg quercetin/g extract, respectively. The order of electron donating abilities of Korean traditional tea water extracts (1 mg/mL) were : rose (96.8%) > green tea (95.3%) > pine needles (71.3%) > chrysanthemum (36.8%) > mulberry (28.9%) ${\qeq}$ persimmon (28.8%). The order of nitrite-scavenging abilities at pH 1.2 (2 mg/mL) was green tea > rose > pine needles > chrysanthemum ${\qeq}$ mulberry ${\qeq}$ persimmon. The order of hydroxyl radical scavenging activity (5 mg/g) was chrysanthemum > mulberry > rose > persimmon leaves > pine needles > green tea. Rose extracts showed antimicrobial activity against Micrococcus luteus, Bacillus cereus, Salmonella enteritidis, and E. coli, whereas green tea extracts showed strong antimicrobial activity aginst S. enteritidis.

• Journal of Life Science
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• v.20 no.3
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• pp.350-355
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• 2010

This study was carried out in order to characterize the flavor of Pueraria radix-green tea. To make a new tea with good flavor and functional properties, Pueraria radix was mixed with green tea. Volatile flavor compounds of Pueraria radix-green tea were extracted by simultaneous distillations and extraction methods using a Likens and Nickerson's extraction apparatus. The concentrated extract was analyzed and identified by GC and GC-MS. Forty-nine compounds including $\beta$-selinene, $\beta$-caryophyllene, hexanal and nonanal were isolated and identified from Pueraria radix. Sixty-four compounds including nerolidol, linalool, linalool oxide and phenylethyl alcohol were isolated and identified from green tea. Eighty-two compounds including linalool, $\delta$-cadinene, limonene, $\beta$-caryophyllene and $\beta$-ionone were isolated and identified from Pueraria radix-green tea.

• Natural Product Sciences
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• v.22 no.4
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• pp.270-274
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• 2016

Green tea, the leaves of Camellia sinsneis (Theaceae), is generally acknowledged as the most consumed beverage with multiple pharmacological functions including antioxidant activity. This study was performed to analyze the effect of extraction conditions of green tea on its antioxidant effects using DPPH assay. Three extraction factors such as extraction solvent (EtOH, 0 - 100%), extraction time (3 - 15 min) and extraction temperature ($10-70^{\circ}C$) were analyzed and optimized extraction condition for antioxidant activity of green tea extract (GTE) was determined using response surface methodology with three-level-three-factor Box-Behnken design (BBD). Regression analysis showed a good fit of data and the optimal conditions of extraction were found to be 57.7% EtOH, 15 min and $70^{\circ}C$. Under this condition, antioxidant activity of experimental data was 88.4% which was almost fit to the ideal value of 88.6%. As epigallocatechin gallate (EGCG) is known for the major ingredient for antioxidant activity of green tea, we investigated the effect of EGCG on antioxidant activity of GTE. EGCG showed antioxidant activity with the $IC_{50}$ value of $4.2{\mu}g/ml$ and a positive correlation was observed between EGCG content and the antioxidant activity of GTE with $R^2=0.7134$. Interestingly, however, GTE with 50 - 70% antioxidant activity contain less than $1.0{\mu}g/ml$ of EGCG, which is much lower than $IC_{50}$ value of EGCG. Therefore, we suppose that EGCG together with other constituents contribute to antioxidant activity of GTE. Taken together, these results suggest that green tea is more beneficial than EGCG alone for antioxidant ability and optimal extraction condition of green tea will be useful for the development of food and pharmaceutical applications

• Journal of Physiology & Pathology in Korean Medicine
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• v.25 no.4
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• pp.608-613
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• 2011

The aqueous Green tea comes to be used with the Oriental medicine plant, it has the numerous health benefits, including antioxidant, anti-inflammatory, and anti- carcinogenic properties. Epidermal progenitor cells give rise to multiple skin lineages: hair follicle, sebaceous gland and the overlying interfollicular epidermis. Sebocytes are the cells of the sebaceous gland, which synthesize and accumulate lipid dropolets. In order to determine the effect of Green tea on lipid production, several experiments were performed in SZ95 cells (sebocytes). We found that Green tea increased lipid droplets compared with control in a dose-dependent manner. Human sebaceous glands produce sebum, a lipid mixture of squalene, wax esters, triglycerides, cholesterol esters, and free fatty acids that is secreted onto the skin. Therefore, to investigate the effects of Green tea on intracellular lipid levels, we treated SZ95 cells with Green tea, and then examined cholesterol and triglyceride levels. After treatment of the cells with Green tea, the cholesterol and triglyceride levels of SZ95 cells were increased significantly in a dose-dependent manner.

• 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.

• Korean Journal of Clinical Laboratory Science
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• v.52 no.4
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• pp.398-407
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• 2020

The inhibitory effect on α-glucosidase, a marker of postprandial hyperglycemia, and angiotensinconverting enzyme (ACE), a marker of hypertension, was analyzed using non-fermented green tea and three different types of fermented tea, which are popular beverages in modern life. Green tea was mixed with trace amounts of vanadate (50 ㎍/mL), which has insulin-mimetic effects, to investigate the synergistic effect of vanadate on the inhibition of α-glucosidase. The concentration of epigallocatechin gallate (EGCG) and caffeine was also checked. The extracts of green tea and fermented teas showed clear inhibition on α-glucosidase, which caused a decrease in the postprandial glucose levels. The inhibitory effect was most prominent in the 20% fermented tea. Trace amounts of vanadate (50 ㎍/mL)-mixed green tea extract had twice the inhibitory effect on α-glucosidase than the pure tea extract. All teas showed inhibitory effects on ACE. Among those, the effect was most prominent in green tea, which had higher concentrations of EGCG. In contrast, the postprandial glucose-lowering effect and ACE inhibition of the fermented teas, which have a lower level of EGCG, was attributed to some other different functional substances.