• Journal of the Korean Society of Food Culture
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• v.24 no.3
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• pp.308-314
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• 2009

In this study, we examined the composition of catechins, theaflavins and alkaloids in leaves during processing to fermented black tea, which is produced by withering, roll breaking, and fermentation of Korean Yabukida tea plant. In addition, we determined the optimal conditions for the production of fermented black tea. The average moisture content in fresh leaves was 70.85%, which dropped to 3.07% in fermented black tea at the last stage of production. When the leaves were analyzed by HPLC, seven types of catechins, four types of theaflavins and three types of alkaloids were identified. The levels of catechins, theaflavins, and alkaloids were then evaluated after being processed into fermented tea. From these experiments, we found that the level of theaflavins, which determines the property of the tea, increased during fermentation. This effect resulted from the change in EGCG, ECG, EGC, EC during the process of fermentation. We also found that the maximal amount of theaflavins was created after 1-2 hours of fermentation. Thus, our results imply that the best condition for producing fermented black tea would be to ferment for 1-2 hours.

• Journal of Life Science
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• v.7 no.4
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• pp.309-315
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• 1997

The fermented black tea with tea fungus (FBTF) was prepared by culturing tea fungus biomass in black tea with 10% sucrose (BT) at 30$\circ$ for 14 days. The flavor quality of FBTF was investigated by sensory and chemical analysis, and the results were compared with BT. The data of sensory analysis indicated that fruity, wine-like, sharp-pungent, and vinegar-like flavor notes were increase, while earthy note was reduced during fermentation. GC-MS analysis of volatile compounds collected from FBTF and BT by Tenax trap showed that linalool, liinalool oxide other flavor compounds known as black tea flavor compounds were disappeared. Some major flavor compounds produced during fermentation were acetic acid, ethanol, limonene, $\alpha$-terpineol, and these volatiles may be attributed to the flavor of characteristic FBTF. Biosynthetic pathway for the formation of limonene and $\alpha$-terpineol are proposed through mevalonic acid pathway using acetic acid as precusor and/or through transformation of linalool and linalool oxide.

• Journal of the Korean Society of Food Science and Nutrition
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• v.32 no.3
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• pp.356-362
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• 2003

The present study was conducted to know the physicochemical properties of non fermented tea and fermented teas with the fermented time of 0 hr (non fermented tea), 10 hrs, 17 hrs (semi-fermented tea), 24 hrs (black tea), respectively The moisture content of non fermented tea, semi fermented, and black tea was 3.01% ~ 3.29%. The contents of reducing sugar, crude lipid, crude protein were increased and that of ascorbic acid was decresed with fermentation. The total contents of those increased as tea was more fermented. The contents of the citric acid and the malic acid were increased with fermentation, but the content of the succinic acid was decreased. However, the total content of organic acid was generally increased with fermentation. The total content of the amino acid was increased with fermentation. In non fermented tea, Thr+theanine, the Asp, and the Glu, were determined in order of content. In semi-fermented tea and black tea, Ter+theanine, Glu, and Asp were determined in order of content. The rate of essential amino acid in the total content of free amino acid was increased with fermentation. The content of theanine was 1.21% in non fermented tea and 1.50% in black tea. The contents of theanine were increased as tea was more fermented. The content of caffein was 3.57% in non fermented tea and 3.55 ~ 3.60% in semi-fermented tea and black tea. These results were inconsistent in the content of caffein. Five kinds of catechin, that is, cathechin, epigallocathechin, epicathechin, epigallocathechin gallate, and epicathechin gallate were extracted. The content of catechin was 14.18% in non fermented tea, but decreased sharply as tea was more fermented.

• Journal of Life Science
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• v.6 no.1
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• pp.56-65
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• 1996

Black tea extractbsupplemented with 10% sucrose was fermented by fungus at 30$\circ$C. A pellicle thick as 7$\sim$8 mm covered entire surface of the medium and the wxtract converted to acidic beverage(abbreviated below as fermented black tea) by 14 days of fermentation. It was a kind of acetic acid fermentation depending on symbiotic microorganisms. During the fermentation strains of yeasts(Saccharomyces cerevisiae and Eeniella sp.)and bacteria(Bacillus subtilis, Kurthia zopfii, Gluconobacter oxydans and Deinicoccus sp.) were isolated from aqueous layer. Contrastly to it, a bacterial strain(Acetobacter aceti) was isolated from thick pellicle. The bacteria grew as a viscouse cluster on solid agar medium differently from usual strains of A. aceti. Fermented black tea had sweet-sour taste and sweet smell.

• Journal of the Korean Society of Food Science and Nutrition
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• v.34 no.6
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• pp.869-874
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• 2005

The purpose of this study was to determine the qualities of loaf breads added with green tea powder, minimum fermented tea powder (fermented for 10 hrs), medium fermented tea powder (fermented for 17 hrs), and black tea powder (fermented for 24 hrs). The moisture content of loaf bread added with green tea and three types of fermented tea was $36.02\~36.44\%$ and was similar to the control group of $36.98\%$. The content of crude protein and ash of loaf bread added with green tea powder and fermented tea was higher than that of control group. The water holding capacity of loaf bread added with green tea powder was the highest and was followed by the fermented tea added group and the control group. The volume and specific volume of loaf bread were high in tile order of the control group, the fermented tea added group, the green tea added group. The lightness of loaf bread got lower, while the redness and the yellowness of the bread 9ot higher as loaf bread was added with more fermented tea. The hardness of loaf bread get higher, but the cohesiveness got lower as loaf bread was added with the more fermented tea. The gumminess and chewiness of loaf bread added with black tea powder were the highest. The result of sensory evaluation of the loaf bread showed that the preference of the color was tBle highest in the control group, while the preference of the flavor and the taste was the highest in the green tea group and the minimum fermented tea group. The preference of overall acceptability of loaf bread was the highest in the minimum fermented tea group.

• Preventive Nutrition and Food Science
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• v.5 no.3
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• pp.165-169
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• 2000

Kombucha beverages were made from sweetened tea by Oriental, European and Tibetan tea fungus starters. The hot water extracts o green tea, black tea, Gugija and Omija were mixed with white and/or brown sugar, and were fermented under a static culture at 3$0^{\circ}C$. Titrable acidity, pH, color and cellulose production in kombucha beverages were evaluated. All tea fungus starters showed a higher acid production in green/black tea extracts rather than Gugija and Omija extracts. In green/black tea extracts Oriental tea fungus produced a kombucha beverage with a higher titrable acidity and lower pH than those of European and Tibetan tea fungus starters. By the static fermentation of green/black tea extract for 18 days, Oriental, Tibetan and European tea fungus starters produced cellulose pellicles of 0.43g, 0.16g, and 0.19 g (dry weight) on the top in the culture, respectively. As a mother starter, the cellulose pellicle was more efficient in acid production compared with tea fungus broth. Oriental/Tibetan mixed tea fungus showed the best acid production in the green/black tea extract supplemented with brown sugar.

• Journal of the Korean Society of Food Science and Nutrition
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• v.24 no.1
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• pp.154-159
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• 1995

Inhibition of xanthine oxidase by tea extracts obtained from non-fermented tea(steamed green tea and roasted green tea), semi-fermented tea(oolong tea) and fermented tea(black tea) were investigated. The crude catechin fraciton had a hgher inhibitory effect against xanthine oxidase, and the effect was increased with the addition of tea extracts. Their inhibitory effect were hardly influenced until extracted three times with hot water. According to the investigation of catechins in the crude catechin fraction obtained from tea extracts, (-)-epicatechin-(EC), (-)-epicatechin gallate(ECg). (-)-epigallocatechin(EGC) and (-)-epigallocatechin gallate(EGCg) were 80.1$\mu\textrm{g}$/mg 113.5$\mu\textrm{g}$ /mg, 186.3$\mu\textrm{g}$/mg and 367.7$\mu\textrm{g}$/mg in steamed green tea, and 75.6$\mu\textrm{g}$/mg, 114.7$\mu\textrm{g}$/mg, 193.7 $\mu\textrm{g}$/mg and 381.9$\mu\textrm{g}$/mg in roasted green tea, and 69.4$\mu\textrm{g}$/mg, 110.0$\mu\textrm{g}$/mg, 127.1$\mu\textrm{g}$.mg and 464.9$\mu\textrm{g}$/mg in oolong tea, and 78.1$\mu\textrm{g}$/mg, 171.8$\mu\textrm{g}$/mg, 80.7$\mu\textrm{g}$/mg and 51.4$\mu\textrm{g}$/mg in black tea, respectively. Order of the content of these catechins was (-)-EGCg>(-)-EGC>(-)-ECg>(-)-EC in steamed green tea, roasted green tea and oolong tea, and was (-)-ECg>(-)-EGC>(-)-EC>(-)-EGCg in black tea. Also the concentration of catechins was hardly influeced until extracted three times. The inhibition ratio of xanthine oxidase by autherntic catechins was hardly influenced until extracted three times. The inhibition ratio of xanthine oxidase by authentic catechins was 94.9% and 87.6% by addition of 5.0$\mu\textrm{g}$/ml of (-)-EGCg and (-)-ECg, respectively. the inhibitors of xanthine oxidase were supposed to be due to (-)-ECg and (-)-EGCg in tea polyphenol compounds.

• The Korean Journal of Food And Nutrition
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• v.18 no.1
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• pp.94-101
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• 2005

The present study was conducted to know the physicochemical properties of Korean tea according to degree of fermention. The moisture content of green tea, blue tea, yellow tea and black tea was 2.02∼2.04%. The content of total nitrogen was 3.78 % in green tea and 3.49∼4.03% in fermented tea. The content of the mineral was highest in Ca, Mg. The content of vitamin C was 670.62 mg in green tea and 169.7∼85.03 mg in fermented tea. The content of vitamin C were increased as tea was more fermented. The composition of vitamin E and β-carotene was green tea> blue tea> yellow tea> black tea. The content of the rutin was 0.12 % in green tea and 1.37% in black tea. The content of rutin was increased with fermentation. The content of total amino acid of green tea was 2270.9 mg. The content of main amino acid of Glu, Asp, and Leu was 342.01 mg, 165.32 mg, and 161.69 mg and the hightst content of Glu. The content of total amino acid of black tea was 2,219.08 mg. Total amino acid content of fermented tea increased in the order of black tea> blue tea> yellow tea, and among the tea, the content of black tea was the highest in the fermented tea. The content of caffeine was 1.17% in green tea and 1.05∼1.32% fermented tea. These results were nothing in the content of caffeine during the fermentation. The content of theanine was 0.95% in green tea and 0.73∼1.42% in fermented tea. The content of total catechin was highest in green tea, and decreased sharply as tea was more fermented. Flavonoid content of 1.05% in green tea. DPPH radical scavenge activities of the teas 4.73∼19.5% mg.

• Journal of Life Science
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• v.6 no.2
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• pp.104-110
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• 1996

The present study was conducted to elucidate the functional property of tea extract obtained from tea extracts, semi-fermented tea(oolong tea) and fermented tea(black tea). Tea extracts exhibited remarkable nitrite-scavenging actions, and the action increased with the increased of the amount of tea extracts. The nitrite-scavenging actionof tea extracts showed pH dependent, highest at pH 1.2 and lowest at pH6.0. The nitrite-scavenging rate in tea extracts/amine/nitrite systems proved to be faster than that in amine/nitrite systems. To screen the nitrite-scavenging factors, tea extracts were fractionated into water-soluble, methanol-soluble, methanol-precipitate and crude catechin fraction. Among these fractions of tea extracts, the crude catechin fraction possessed greater nitrite-scavenging action than the other fractions. The nitrite-scavenging action of tea extracts increased with the contents of total phenols and an absorbance at 280nm, nitrite-scavenging factors were supposed to be and catechins in tea polyphenol compounds.

• Journal of Convergence for Information Technology
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• v.11 no.3
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• pp.194-204
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• 2021

The reason why domestic fermented tea is less recognized than the world's top three black[Sri Lanka Uva black tea, India Darjeeling black tea, China Keemun(祁門) black tea] teas is that there is a very lack of scientific basis for clear quality standards and functionality. This researcher identified the major components of the world's top three black teas and fermented teas derived from domestic wild tea trees through analysis of various instruments such as HPLC, TOF-MS, and ELISA reader. In addition, in order to compare the physiological activity of the world's three major black teas and domestic fermented teas, the biological activity was compared and analyzed through DPPH·ABTS free radical scavenging activity and NO production inhibition. Furthermore, comparative analysis data on organic acid, free sugar, and tannic acid were obtained for quality comparison of palatable foods. When the above results are summarized, it is believed that it is possible to present the quality standards of Korean tea, and it is expected that the globalization of Korean tea will be possible.