• Journal of the Korean Society of Food Science and Nutrition
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• v.32 no.7
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• pp.1011-1020
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• 2003

The present study was conducted to examine sensory characteristics of non-fermented tea and fermented teas with fermented times of 0 hr (green tea), 10 hrs (mild fermented tea), 17 hrs (medium fermented tea), 24 hrs (black tea), respectively. The lightness of tea powder and tea extract got lower, and the redness and the yellowness of those got higher as tea was more fermented. The result of sensory evaluation about the extracts of non fermented tea and fermented teas showed that the preference of flavor got higher in the more fermented tea but one got lower in a mild fermented tea according to temperatures, respectively. The preference of taste got higher at 60∼7$0^{\circ}C$ extracts in the green tea and got the highest at 80∼9$0^{\circ}C$ extracts in the medium fermented tea and black tea. A total of 76 flavor components was detected in non fermented tea and the total contents of those were 129.9 mg/kg. The major components were linalool, geraniol, nerolidol, benzyl alcohol, and linalool oxide. A total of 76 flavor components was detected in the mild fermented tea and total contents of those were 159.1 mg/kg. The major components were geraniol, linalool, linalool oxide, ethanol, benzyl alcohol, etc and were similar in those to the non fermented tea. A total of 79 flavor components was detected in the medium fermented tea and total contents of those were 455.6mg/kg. The major components were ethyl acetate, 3-methylbutanal, ethanol, (E)-2-hexenal, geraniol, linalooloxide. A total of 79 flavor components was detected in the Black tea and total contents of those were 680.5 mg/kg. The major components were 3-methylbutanal, ethyl acetate, geraniol, ethanol, (E)-2-hexenal, hexanal, linalooloxide. The amounts of flavor components was increased, but the amounts of aldehyde compounds was remarkably increased according to the degree of fermentation.

• Korean Journal of Food Science and Technology
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• v.28 no.3
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• pp.405-410
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• 1996

The fermented black tea with tea fungus (FBTF) known to cure various diseases was prepared by culturing tea fungus biomass in black tae with different kinds (sucrose, glucose, fructose and corn syrup) and concentrations (10-60% m/v) of saccharides. pH changes and total acid production of FBTF were investigated during 14 dats incubation at $5-45^{\circ}C$ The patterns of acid production in sucrose and fructose black tea solution were similar each other, and those in glucose and corn syrup black tea solution were similar each other showing that tea fungus biomass utilizes fructose than glucose more efficiently. The optimum incubation temperature for the formation and growth of tea fungus Biomass, and the acid production was $30^{\circ}C$ Low contents of total aids (0.1%-0.2%) were produced in 20% of higher concentrations of sucrose and fructose black tea solution, while 1.8% and 0.68% were produced in the 10% of sucrose and fructose black tea solutions, respectively, pH of FBTF dropped to 2.74-3.56 after 2 days of incubation of all the culture solution and Kept this level to 14 days incubation.

• 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.

• Korean Journal of Microbiology
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• v.53 no.3
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• pp.170-179
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• 2017

Tea is the most popular beverage in the world. In fact, there are mainly three different kinds of tea (Green tea, black tea, and post-fermented tea). Post-fermented tea is produced by the microbial fermentation process using sun-dried green tea leaves (Camellia sinensis) as the raw material. Chungtaejeon was a traditional tea introduced in the age of the ancient three states and is the only "Ddeok-cha or Don-cha" culture in the world that survived on the southwestern shore of Republic of Korea. In this study, the structures of the bacterial community involved in the production of oriental traditional post-fermented tea (Chungtaejeon) were investigated using 16S rRNA gene analysis. The 16S rRNA gene analysis of dominant microbial bacteria in post-fermented tea confirmed the presence of Pantoea sp., and Klebsiella oxytoca. Phylogenetic analysis suggested that the taxonomic affiliation of the dominant species in the post-fermented tea was ${\gamma}$-proteobacteria. As a result of the microbial community size analysis, it was confirmed that the size of the microbial communities of Chungtaejeon was the largest compared to other teas

• Journal of Biosystems Engineering
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• v.41 no.2
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• pp.85-92
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• 2016

Background: The same plant, Camellia sinensis, is used to produce all types of tea, and the differences among the various types arise from the different processing steps that are used. Based on the degree of fermentation, tea can be classified as black, green, white, or oolong tea. Of these, black tea is the most or fully fermented tea. The oxidized polyphenolic compounds such as theaflavins (TF) and thearubigins (TR) formed during fermentation are responsible for the color, taste, flavor, and aroma of black tea. Results: Research indicates that an optimum ratio of TF and TR (1:10) is required to ensure a quality cup of tea. The concentrations of TF and TR as well as desirable quality characteristics increase as fermentation time increases, reaching optimum levels and then degrading if the fermentation time is prolonged. It is also necessary to control the environment for oxidation. There are no established environment conditions that must be maintained during the fermentation of the ruptured tea leaves. However, in most cases, the process is performed at a temperature of $24-29^{\circ}C$ for 2-4 h or 55-110 min for orthodox tea or crush, tear, and curl (CTC) black tea, respectively, under a high relative humidity of 95-98% with an adequate amount of oxygen. Conclusion: The polyphenolic compounds in black tea such as TF and TR as well as un-oxidized catechins are responsible for the health benefits of tea consumption. Tea is rich in natural antioxidant activities and is reported to have great potential for the management of various types of cancers, oral health problems, heart disease and stroke, and diabetes and to have other health benefits such as the ability to detoxify, improve urine and blood flow, stimulate, and improve the immune system.

• Preventive Nutrition and Food Science
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• v.12 no.1
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• pp.7-10
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• 2007

Theaflavins (TF) and thearubigins (TR) were separated from Korean microbially fermented tea leaves. Contents of TF (74.4 $\mu$M/g) and TR (37.2%) were higher than reported for black tea fermented by oxidase. Antioxidant activities of TF, TR and EGCG were analyzed and protective effects of COS-7 cells against copper and cadmium-induced toxicity were investigated. TF and TR exhibited good inhibition rates of about 85$\sim$90% for antioxidant and scavenging activities of free radicals and protected COS-7 cells against apoptosis or damage caused by stress, such as cadmium and copper-oxidative injury, free radicals etc. These results indicate that TF, TR and EGCG have antioxidant and scavenging activities against free radicals and protect COS-7 cells from Cu, Cd induced injury.

• 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.

• Food Science and Industry
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• v.40 no.3
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• pp.59-65
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• 2007

• Journal of the Korean Society of Food Science and Nutrition
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• v.37 no.3
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• pp.367-372
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• 2008

Yukwa were added with non-fermented tea (Bucho-cha and Okro-cha), semi-fermented tea (Ooreung-cha), and fermented tea (black tea) to investigate the effect of different kinds of tea powder on quality characteristics of Yukwa during storage. Yukwa samples were used for analysis such as crude lipid, moisture, texture, antioxidative property (TBA value), and sensory test. There were no significant differences on crude lipid, moisture, and texture analysis. Green tea powder treatment showed strong antioxidant activity. In particular, antioxidant property of non-fermented tea exhibited a higher antioxidative effect than that of the other samples. Sensory evaluation showed that sensory scores of samples added with non-fermented tea were significantly higher than the other samples, indicating that the addition with 0.1% of non-fermented tea powder could contribute to the improvement of quality and shelf-life of Yukwa during storage.

• Journal of Applied Biological Chemistry
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• v.56 no.2
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• pp.113-117
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• 2013

Ten major residual biogenic amines including toxic histamine and tyramine were investigated in the plant-based minor Korean fermented food. From the analyses of pickled vegetables, fermented vegetable extracts, fermented tea, black garlic and herbal rice wines, more than 100 mg/kg of histamine were found in pickled soy leaf and pickled mulberry leaf, and also over 1,000 mg/kg of total biogenic amines were found in pickled soy leaf. No sample was found over in black garlic, fermented tea, fermented vegetable extracts and herbal rice wine, less than 100 mg/kg of histamine and/or 1,000 mg/kg of total biogenic amines were observed. Interestingly, all the tested rice wines were found to be over 100 mg/kg of agmatine residue.