• Food Science and Preservation
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• v.18 no.1
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• pp.46-52
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• 2011

Wild grape juice was fermented by Gluconacetobacter hansenii TF-2 isolated from tea fungus, to develop a new acidic beverage (fermented wild grape beverage, WGB). Broth was prepared by fermentation of 11~17% (v/v) juice, and sweetened with sucrose (initial sucrose level: $10^{\circ}$ Brix). Fermentation was initiated by addition of 5% (w/v) seed gel (the pellicle of the tea fungus) which had been previously cultured in the same medium (freshjuice broth), and fermentation proceeded in the dark at $29{\pm}1^{\circ}C$ for about 15 days. The major acids produced were succinic acid, malic acid, and acetic acid. After 15 days of fermentation, the organic acid content (principally succinic acid) was 49.6 ppm in WGB 11 and 77.4 ppm in WGB 17. The free sugar content of WGB was 1063.6-1082.5 mg/mL, composed of unfermented fructose, glucose, and sucrose, in that order. The microbial inhibitory effects of the fermented beverage were most apparent when Gram-negative bacteria (Escherichia coli and Salmonella typhimurium) were tested; the inhibition rate was 34.46-88.00%. The new fermented beverage thus displays effective antimicrobial activity against some species of bacteria.

• Food Science and Preservation
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• v.30 no.6
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• pp.1043-1055
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• 2023

This study was conducted to suggest an extraction method for preparing the extract from green tea leaves that possess enhanced antioxidant and antibacterial activities. Different ethanol concentrations were tested to recover phenolics and flavonoids, and 50% ethanol was the best under heat treatment (121℃, 15 min). The ethanol extract exhibited excellent DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging activity and growth inhibition against B. cereus, B. licheniformis, S. aureus subsp. aureus, and A. hydrophila subsp. hydrophila. To enhance the antioxidant and antibacterial activities, cell-wall degrading enzymes (2.5% cellulose+2.5% pectinase, v/w dry sample) treatment and Saccharomyces cerevisiae fermentation were applied singly or in combination. The enzymatic treatment of green tea leaves notably increased extraction yield. However, the antioxidant and antibacterial activities of the extract were lower than those of the control (heat-treated 50% ethanol extract). In contrast, the yeast fermentation alone did not affect the yield, but enhanced antioxidant and antibacterial activities, contributing to the increase in the extract's total phenolic and flavonoid contents.

• Journal of Microbiology and Biotechnology
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• v.19 no.4
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• pp.397-402
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• 2009

Kombucha tea(KT) is sugared black tea fermented with a symbiotic culture of acetic acid bacteria and yeasts, which is said to be tea fungus. KT is claimed to have various beneficial effects on human health, but there is very little scientific evidence available in the literature. In the present study, KT along with black tea(BT) and black tea manufactured with tea fungus enzymes(enzyme-processed tea, ET) were evaluated for hepatoprotective and curative properties against $CCl_4$-induced toxicity, using male albino rats as an experimental model by analyzing aspartate transaminase, alanine transaminase, and alkaline phosphatase in plasma and malondialdehyde content in plasma and liver tissues. Histopathological analysis of liver tissue was also included. Results showed that BT, ET, and KT have the potential to revert the $CCl_4$-induced hepatotoxicity. Among the three types of teas tried, KT was found to be more efficient than BT and ET. Antioxidant molecules produced during the fermentation period could be the reason for the efficient hepatoprotective and curative properties of KT against $CCl_4$-induced hepatotoxicity.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.48 no.1
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• pp.47-53
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• 2022

In this study, the conditions for efficiently extracting polyphenols contained in black tea were optimized. In order to confirm the polyphenol content according to the degree of fermentation, the polyphenol content in black tea of the three fermentation degrees was compared. As the degree of fermentation increased, the polyphenol content increased, and it was confirmed that the theabrownin content, the largest in size, increased significantly. In addition, it was confirmed that the amount of theabrownin extraction increased by about 150% or more compared to other extraction water when extracting using mineral water, which was hard water. The antioxidant effects of black tea extract and the theabrownin was confirmed using ABTS assay. As a result, both extracts had antioxidant effects, and IC₅₀ values were confirmed to be 10.60 ppm and 13.21 ppm, respectively. And also, the anti-inflammatory effect of the theabrownin was confirmed that the mRNA expression of IL-8 increased by UVB irradiation was inhibited in a concentration dependent manner by the theabrownin. In addition, when theabrownin was treated with 10 ppm, the mitochondrial function decreased by UVB irradiation was restored to 86 ± 1.9% compared to the control group. Therefore, we concluded that theabrownin could protect mitochondrial damage caused by UVB irradiation.

• Journal of the Korean Society of Food Science and Nutrition
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• v.34 no.2
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• pp.148-157
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• 2005

This study was investigated to determine antimicrobial activity of the water and ethanol extracts of Korean wild green tea, semi-fermented tea, and fermented tea. Antimicrobial activity was examined against 8 kinds of several microorganisms. The minimum inhibitory concentration (MIC) of the water and ethanol extracts of green tea showed the most active antimicrobial activity against B. subtilis 0.2 mg/mL in Gram positive bacteria and P. fluorescens 0.3∼0.5 mg/mL in Gram negative bacteria. But the extracts did not show antimicrobial activity against lactic acid bacteria and yeast at the level of less than 1 mg/mL. Antimicrobial activity got lower as tea got more fermented. Antimicrobial activity of ethanol extracts from green tea, semifermented tea, and fermented tea was stronger than that of water extracts. Antimicrobial activity of the water and ethanol extracts of green tea, semi-fermented tea, and fermented tea was not destroyed at 50∼121$^{\circ}C$, and pH 3∼11, which proved to be very stable when given over heat, acid & alkali treatment. The ethanol extract of green tea, semi-fermented tea, and fermented tea was fractionated in the order of hexane, diethyl ether, ethyl acetate and water fraction. The highest antimicrobial activity was found in the water fraction, but not found in hexane fraction, while antimicrobial activity of fermented tea was not found in ether fraction.

• Culinary science and hospitality research
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• v.21 no.2
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• pp.230-242
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• 2015

The purpose of this study is to investigate the quality characteristics of bread added with different levels of Pu'er tea. The overall effects of Pu'er tea on white pan bread were examined through mixograph, fermentation rates, TPA, volumes, crumbScan, color value, moisture content, and sensory evaluation. The result of the mixogram showed that all samples were found to be adequate between 3 and 5 minutes of peak time and their peak values were at 60%. Among the samples, PRaw15 had the highest fermentation rate, and it showed the lowest hardness in TPA. In addition, PRaw15 had the highest specific volume and moisture content. The results of the crumbScan showed that there were significant differences in crumb fineness, volume, and thickness between the samples. Color value also exhibited significant differences between the samples. The acceptance test showed that PRipe15 had the best overall acceptance. In conclusion, Pu'er tea affects the quality of dough and bread. Therefore, Pu'er tea could be added when bread is baked for improved health and better quality of the bread.

• Asian-Australasian Journal of Animal Sciences
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• v.20 no.6
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• pp.920-924
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• 2007

Two experiments were carried out on a laboratory scale. The first involved a study of the effect of green tea on characteristics of fermented juice of epiphytic lactic acid bacteria (FJLB). FJLB was treated with 50 g/L of green tea products as follows: new shoot powder (FJLB+N), leaf powder (FJLB+L), commercial powder (FJLB+P), sterilized new shoot powder (FJLB+SN), sterilized leaf powder (FJLB+SL) or sterilized commercial powder (FJLB+SP). FJLB without any additive was also prepared (Untreated FJLB). After incubation, the number of microorganisms in FJLB were studied. Subsequently, these FJLB were applied at 10 ml/kg to chopped rhodesgrass to study their effects on fermentation. Compared with untreated FJLB, the addition of green tea increased (p<0.05) lactic acid bacteria (LAB) and also aerobic bacteria counts in FJLB. At 60 d of ensiling, all the FJLB treated silages were well preserved, pH and butyric acid content were lower (p<0.001) and lactic acid was higher (p<0.001) than that of the control. Lactic acid content was significantly higher (p<0.001) with treated FJLB than with untreated FJLB. FJLB treated with sterilized green tea decreased (p<0.001) the pH and the lactic acid content was higher (p<0.001) than that in the unsterilized green tea silages.

• Korean Journal of Food Science and Technology
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• v.13 no.4
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• pp.267-272
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• 1981

The qualities of ginseng leaf teas prepared by six different processing methods were evaluated to develop the leaf tea. The leaf tea prepared by fermentation at $30^{\circ}C$ showed the highest in the ratio of 30 min water extracts to the total extractable matters. This ratio was followed in decreasing order by the heat dried tea and the one fermented at $25^{\circ}C$. The yellow, orange and red color intensities of water extracts were the highest in the tea prepared by toasting method followed by teas fermented at $30^{\circ}C\:and\:25^{\circ}C$. The amount of saponins extracted with boiling water was the highest in the tea fermented at $30^{\circ}C$ among teas investigated. This tea was also most acceptable in sensory evaluation by the flavour profile method.

• Korean journal of food and cookery science
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• v.16 no.6
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• pp.663-669
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• 2000

As an attempt to develop new functional beverages, various ingredients including pine needle, P Japonica, C. Militaris, black tea, artemisia, cocoa, and persimmon leave tea, were used to make fermented beverages and their chemical and sensory properties were evaluated. The acidity of beverages produced was the highest in the one with C. Militaris, and the lowest in the ones with persimmon leave tea and pine needle. The pH of P Japonica beverage, 2.54, was the lowest among all. The sugar content was the highest in the one of C. Militaris and the lowest in cocoa-used one. In sensory evaluation, the fermented beverages prepared with persimmon leave tea, pine needle, and artemisia were significantly more preferable in acceptability than the others (p<.001). For purchase intention, the beverage prepared with persimmon leave tea got the highest score followed by the ones with pine needle and artemisia, and the scores of those three beverages were significantly higher than the others (p<.001). Hunter color test showed that fermented beverage added Black tea was the lowest in lightness, but the highest in redness and yet-lowness(p<.001). The beverages with high scores in sweet odor, sweet taste, and purchase intention were more favored in the sensory evaluation looking at the correlation among the sensory properties. And the lightness in color had a positive correlation, and the redness and yellowness had negative correlations with appearance quality of the beverages. Chemical properties like pH and acidity were negatively correlated with the acceptability, and the sugar content was positively correlated with sweet odor.

• Journal of the Korean Society of Food Science and Nutrition
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• v.36 no.1
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• pp.1-7
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• 2007

Antimutagenic and in vitro anticancer effects of doenjangs added with green tea extract and/or using bamboo salt were studied by Ames test using Salmonella enterica serovar Typhimurium (Salmonella Typhimurium) TA100 and 3-(4,5-dimethylthiazol) -2,5-diphenyltetrazolium bromide (MTT) assay on PC-3 and DU145 human prostate cancer cells, respectively. At the 1.25 mg/plate concentration, 1% green tea extract (GTE) added doenjang exhibited 85% antimutagenicity against aflatoxin $B_1$ ($AFB_1$), while the control doenjang revealed 63% antimutagenicity, showing increased antimutagenic effect by the addition of green tea extract during doenjang fermentation. GTE added doenjang also increased antimutagenic effect against MNNG. The inhibition rate of the control doenjang showed 34% at 0.625 mg/plate, while 1% and 2% GTE added doenjangs inhibited by 56% and 73% at the 0.625 and 1.25 mg/plate, respectively (p<0.05). In MTT assay, GTE added doenjangs caused 70% $\sim$ 77% inhibition on the proliferation of PC-3 human prostate cancer cells at 0.5 mg/mL while the control doenjang exhibited 46% inhibition. However, 2% GTE added doenjang showed 91% inhibition at 1.0 mg/mL. The trend of the inhibition rate was similar in DU14S human prostate adenocarcinoma cells. When bamboo salt was used instead of natural sea salt, the antimutagenicity against MNNG and in vitro anticancer effect on the prostate cancer cells greatly increased. From these results, it can be concluded that green tea extract addition to doenjang and the use of bamboo salt during doengjang preparation increased the antimutagenic and in vitro anticancer activities of the doenjang and showed a synergistic effect.