• Asian-Australasian Journal of Animal Sciences
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• v.27 no.7
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• pp.937-945
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• 2014

Green and black tea by-products, obtained from ready-made tea industry, were ensiled at $10^{\circ}C$, $20^{\circ}C$, and $30^{\circ}C$. Green tea by-product silage (GTS) and black tea by-product silage (BTS) were opened at 5, 10, 45 days after ensiling. Fermentation characteristics and nutrient composition, including tannins, were monitored and the silages on day 45 were subjected to in vitro ruminal fermentation to assess anti-nutritive effects of tannins using polyethylene glycol (PEG) as a tannin-binding agent. Results showed that the GTS and BTS silages were stable and fermented slightly when ensiled at $10^{\circ}C$. The GTS stored at $20^{\circ}C$ and $30^{\circ}C$ showed rapid pH decline and high acetic acid concentration. The BTS was fermented gradually with moderate change of pH and acid concentration. Acetic acid was the main acid product of fermentation in both GTS and BTS. The contents of total extractable phenolics and total extractable tannins in both silages were unaffected by storage temperatures, but condensed tannins in GTS were less when stored at high temperature. The GTS showed no PEG response on in vitro gas production, and revealed only a small increase by PEG on $NH_3$-N concentration. Storage temperature of GTS did not affect the extent of PEG response to both gas production and $NH_3$-N concentration. On the other hand, addition of PEG on BTS markedly increased both the gas production and $NH_3$-N concentration at any ensiled temperature. It can be concluded that tannins in both GTS and BTS suppressed rumen fermentation, and tannins in GTS did more weakly than that in BTS. Ensiling temperature for both tea by-products did not affect the tannin's activity in the rumen.

• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.7
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• pp.1079-1084
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• 2004

The present study was conducted to compare antioxidant activity of green teas, fermented teas and other related common teas by examining radical scavenging activity using DPPH (2,2 diphenyl l-picryl hydrazyl). Scavenging activity ($SC_{50}$/) of epigallocatechin gallate (EGCG) for 0.1 mM DPPH radical was 5.5 $\mu$M or 4.2 mg/L by weight, then catechin, 14 $\mu$M or 2.5 mg/L and vitamin C, 22 $\mu$M or 3.9 mg/L, respectively. Kyokuro tea (okro) powder of 24.2 mg/L or green tea powder of 25.2 mg/L was used to reach $SC_{50}$/ for 0.1 mM DPPH. One serving of 2 g green tea provides antioxidant activity equivalent to 109∼147 mg EGCG, 145∼185 mg catechin or 131∼168 mg vitamin C. Teas from the first harvest had the highest radical scavenging activity when compared with later harvest green teas grown in the same region, but there is virtually no difference by the harvest time. A Chinese green tea, Dragon well had the highest antioxidant activity among other green teas tested providing antioxidant capacity equivalent to 168 mg EGCG or 188 mg vitamin C per 2 g serving, but partially fermented Chinese teas had much lower antioxidant activity than any green tea tested. Black tea which is fully fermented showed as strong antioxidant activity as green teas (76.3 mg vs 86.7∼67.6 mg per tea bag). One tea bag of green teas from market provided antioxidant capacity equivalent to 52∼86 mg EGCG, 70∼105 mg catechin or 63-96 mg vitamin C. Teas made of persimmon leaf, pine needle, mulberry leaf had comparatively low anti-oxidant activity equivalent to 2.5∼4.8 mg EGCG or 15∼21 mg vitamin C per teabag. The third brewed green tea still had enough antioxidant activity, while tea from tea bag brewed for 3 min or 5 min did not have any difference in their antioxidant activity. More systemic studies are needed to clarify the relationship between tea catechins and antioxidant capacity focusing on how growing, harvest time, fermentation and other processes can influence on this.

• Journal of the East Asian Society of Dietary Life
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• v.20 no.2
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• pp.279-290
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• 2010

Sensory analysis and quality properties were performed on post-aged doenjang (fermented soybean pastes) in order to elucidate the contribution of citrus, green tea and cactus powder to their sensory evaluation. The doenjang added citrus fruits, green tea and cactus powder used a concentration of 0, 3 and 7% (w/w) at 4, 20, $30^{\circ}C$ respectively and analyzed the proximate composition, pH, salt, mineral and amino acid contents after 60 days. Moisture and protein changes during ripening did not show any significant difference. The pH showed lower in the doenjang added citrus and cactus powder than no added soybean paste. The glutamic acid content of doenjang added citrus fruits showed a little decreasing value although there were no differences between samples with various addition contents. Sensory evaluation of doenjang showed that there were no significant differences in preference in the case of added green tea and cactus powder; However, the flavor significantly increased doenjang added 3% citrus powder at $30^{\circ}C$. These results showed that the preference of doenjang containing 3% citrus powder was superior to green tea and cactus powder.

• Microbiology and Biotechnology Letters
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• v.45 no.1
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• pp.71-80
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• 2017

Tea is the most popular beverage in the world. The three main types are green, black, and post-fermented. Post-fermented teas are produced by the microbial fermentation of sun-dried green tea leaves (Camellia sinensis). In this study, the composition of the bacterial communities involved in the production of traditional oriental post-fermented teas (Korean algacha, dancha, and Chinese pu-erh) were investigated using 16S rRNA gene analysis. The dominant microorganisms present in the post-fermented teas included the ${\alpha}$-proteobacteria Rhodobacteraceae and Sphingomonas, and the ${\gamma}$-proteobacteria Pantoea. Cluster analysis confirmed that the microbial populations present in both Korean and Chinese post-fermented teas grouped into the same class. Interestingly, the dominant microorganism present in the Korean post-fermented teas was a bacterium, while for the Chinese post-fermented tea, it was a fungus.

• Korean Journal of Food Science and Technology
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• v.42 no.1
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• pp.21-26
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• 2010

Microbial-fermented tea (MFT), which is made by microorganisms through fermentation, is a popular beverage in Asia, especially in the Yunnam province, China. In this study, changes of the chemical constituents and antioxidant activity during the manufacturing process of MFT were investigated. MFT were respectively prepared from fresh leaves of three different tea species (Yabukita, Daecha, and Korean wild cultivar) and a processed green tea (Korean wild cultivar). The color of the tea infusions gradually changed to red and yellow as a function of fermentation time. Total nitrogen and caffeine contents were not significantly changed. Whereas, the chlorophyll, tannin, and total catechins contents gradually decreased. Interestingly, the epicatechin and epigallocatechin contents increased up to 25 days of fermentation and then decreased. Change of the chemical constituents of all samples showed the same patterns. The antioxidant activity of MFT from Daecha and Yabukita slightly decreased as increasing fermentation time. However, the range over which the antioxidant activity of MFT from Korean wild cultivar and green tea were not changed. This research suggests that it may be possible to manufacturing possibility of MFT using Korean wild cultivar and processed green tea.

• Food Science and Preservation
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• v.9 no.4
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• pp.406-410
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• 2002

This study was conducted to investigate the effect of addition methods of green tea on the fermentation characteristics of kimchi. Kimchis were prepared to 3 methods such as Chinese cabbage soaked in brine containing 1％ of green tea extracts(Ⅰ), salted the cabbage soaked in water containing 1％ of green tea extracts(II), salted the cabbage mixed with seasonings containing 1％ of green tea extracts(Ⅲ), and fermented at l0$\^{C}$. pH of Ⅰ∼Ⅲ kimchis were higher than that of control kimchi during fermentation and its acidity showed the same tendency. Total microbe(5.40∼8.38 log cfu/mL) and the number of lactic acid bacteria(4.99∼8.07 log cfu/mL) in Ⅰ∼Ⅲ kimchis were lower than those of control kimchi(6.16∼9.29 and 4.59∼8.42 log cfu/mL). Lightness of kimchi tissue showed the order of Ⅰ＜II＜control＜Ⅲ. Sour taste and fishy taste of Ⅰ∼Ⅲ kimchis were lower than that of control kimchi. Overall quality was best in II estimated by sensory evaluation and fermentation characteristics.

• Korean Journal of Food Science and Technology
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• v.45 no.4
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• pp.488-494
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• 2013

The anti-diabetic effect of green tea fermented by cheonggukjang was evaluated using KK-$A^y$ mice, an animal model of type 2 diabetes mellitus. Over a 90 day testing period, food and water intake decreased significantly in the group fed fermented green tea (FGT) and a group fed commercially available health functional food (PC), when compared with a diabetic control group (DC). The blood glucose levels of FGT mice were lower than in DC mice throughout the test period and were similar to the levels in PC after 60 days. Levels of Hemoglobin A1c (HbA1c) levels and insulin resistance were lower in mice of the FGT group than in mice of the DC group. DNA microarray analysis showed that administration of FGT increased the abundance of 12 mRNA transcripts related to diabetes. Whereas FGT increased hexokinase transcripts related to glycolysis more than 37 fold, levels of Pdx1 (pancreatic and duodenal homeobox1) and Cacna1e (calcium channel) transcripts increased more than 1.8 fold.

• The Korean Journal of Food And Nutrition
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• v.18 no.4
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• pp.325-333
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• 2005

This experiment was carried out to investigate the effect of green tea powder on the growth and acid production of lactic culture in reconstituted skim milk. The supplementation level of green tea powder to reconstituted skim milk was $0.5\%,\;1.0\%,\;1.5\%,\;2.0\%\;and\;2.5\%$. Reconstituted skim milk containing green tea powder was fermented by single or mixed culture of Streptococcus thermophilus, Lactobacillus acidophilus and Lactobacillus casei. Supplementation of green tea powder did not significantly stimulate growth and acid production of Streptococcus thermophilus and Lactobacillus casei. But the growth and acid production of Lactobacillus acidophilus were slightly enhanced by the addition of green tea powder. When green tea powder was added to reconstituted skim milk at the level of $0.5\%\;or\;1.0\%$, all mixed cultures oi lactic acid bacteria showed high number of viable cell count and the acid production than 3 kinds of single cultures. Therefore, it was suggested to manufacture the yoghurt with the addition of $0.5\~1.0\%$ green tea powder and the inoculation of mixed cultures of lactic acid bacteria for on the stimulation of growth of the lactic culture.

• Korean Journal of Food Science and Technology
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• v.53 no.4
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• pp.454-462
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• 2021

This study investigated the antioxidant and nitric oxide (NO) inhibition effects of three domestic and seven foreign fermented black tea 70% ethanol extracts. Bosung showed the highest total polyphenol and tannin contents. Jeju showed the highest total flavonoid contents. The theanine content was higher in Hadong (651.50 mg%) than in foreign fermented black tea. At 25 ㎍/mL, the domestic fermented black tea extract showed the highest DPPH and ABTS racial-scavenging activities, reducing power assays. Domestic fermented black tea showed higher NO inhibitor activity than foreign black tea at 50 ㎍/mL. Bosung black tea extract showed an increase in SOD-1 level (1.39-fold) compared to the LPS-only group. Bosung and Jeju decreased the GST protein by 1.52- and 1.46-folds, respectively, compared to the LPS-only group. Thus our results suggest that domestic fermented black tea (Bosung, Jeju, and Hadong) are effective antioxidants in RAW 264.7 cells.

• Journal of Animal Science and Technology
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• v.54 no.4
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• pp.299-305
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• 2012

This study was conducted to compare the microbial and physico-chemical quality characteristics in Kimchi-fermented sausages added with sodium nitrite (SN) and green tea extract (GTE). The sausages were fermented at $24^{\circ}C$/RH 89% for 17 hr and then dried at $10^{\circ}C$/RH 70~80% for 9 days. The total bacteria count, lactic acid bacteria count and pH value ranged from 8.7 Log CFU/g sausage, 8.1~8.3 Log CFU/g sausage and 4.35~4.36, respectively, at 9 d of ripening, but did not show significant differences during ripening among all sausages. The lipid oxidation (TBARS) was inhibited by both GTE and SN, but GTE had lower (p<0.05) inhibitory effect, compared with SN. The $b^*$ value of GTE-added sausage was higher than that of the control sausage, but $a^*$ and $b^*$ values of SN-added sausage remained higher than other sausages during ripening. Therefore, it had lower effect on lipid oxidation and color stabilities than SN while GTE improved the lipid oxidation stability in Kimchi-fermented sausage. However, both GTE and SN did not influence the growth of lactic acid bacteria.