• Korean Journal of Food Science and Technology
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• v.24 no.2
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• pp.177-179
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• 1992

The theanine contents of commercial green teas manufactured by the different harves times(1st tea, 2nd tea and 3rd tea) and processes(steamed and parched teas) were determined by amino acid analyzer. There were remarkable differences in the theanine contents among teas of the different harvest times. The theanine content in 1st steamed green tea was 2235 mg% and one in 1st parched green tea was 2106 mg%. The theanine contents in 2nd, 3rd tea were gradually decreased. There were slight differences in the theanine contents among teas of the different process.

• Journal of the Korean Applied Science and Technology
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• v.30 no.4
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• pp.761-769
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• 2013

This study used HPLC to analyze the contents of catechins, alkaloids, theanine, total phenolic compounds and antioxidant activities of commercial Hadong green tea leaves(Uzen, Sezak, Jungzak, Daezak). The content of catechins, alkaloids, theanine, total phenolic compounds were lower by water extracts than by 80% ethanol-water extracts. Total catechin and alkaloid contents in Uzen(172.33 mg/g, 30.80 mg/g) by 80% ethanol extract were the highest. Theanine contents of 80% ethanol-water extracts ranged form 55.36 to 37.48 mg/g of tea leaves. Total phenloic compounds contents of green tea were higher than Uzen. Antioxidative of green tea by DPPH, FTC, TBA method were higher than that Uzen.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.49 no.4
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• pp.295-299
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• 2004

The prices of domestic green tea products are relatively expensive and price differences within products of the same levels of quality are various. Also, there is no basic criteria on evaluation of green tea quality. To group 43 commercial green tea products into several parts by the principal component and cluster analyses, this work was done by use of 8 chemical constituents which were analyzed by NIR system. The principal component and cluster analyses revealed 8 groups. The first group included 16 products that had lower free amino acid and theanine contents. The second group included 5 products having higher free amino acid and theanine contents, but lower ash contents. The third group included 13 products showing medium values of 8 constituents. The IV group included 4 products having higher contents of moisture, free amino acids, and theanine. The V group included 1 product showing higher moisture but lower catechins contents. The VI group included 2 products that had higher moisture and catechins contents, but lower free amino acid and theanine contents. The VII group had higher moisture and catechins contents. The VIII group had higher ash and vitamin C contents. The free amino acid contents which were the most important in flavor evaluation of green tea quality did highly positively correlate with the contents of total nitrogen $(0.956^{**}),\;theanine\;(0.981^{**}),\;and\;caffeine\;(0.793^{**})$, but negatively with the contents of ash $(-0.884^{**})$. The catechins used as for functional ingredients did correlate with contents of caffeine(+) and vitamin C(-), respectively.

• Applied Biological Chemistry
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• v.31 no.3
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• pp.284-291
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• 1988

To establish the evaluation method of Korean green tea, the correlation between physicochemical characteristics and sensory scores by the expert panels were investigated using 15 kinds of green tea manufactured in 1985 from Korea, Taiwan and Japan. Tannin, caffeine and total free amino acid contents of Korean green tea are higher than foreign ones, but the chlorophyll content is the highest in Japanese high grade green tea. Sixteen free amino acids including theanine were identified, and theanine, glutamic acid, aspartic acid and arginine contents which affect the brothy taste of green tea infusion were highest in Korean green tea. Sensory score for the color of Korean green tea infusion were lower than Japanese tea, but the flavor and taste were the best. In multiple regression analysis, the quality affecting factors of the green tea were elucidated as the caffeine$(X_1)$, chlorophyll b$(X_2)$, total free amino acid contents$(X_3)$, and L value$(X_4)$ of green tea infusion. The regression equation was expressed as $Y=-21.5820+2.1691X_1+0.0130X_2+0.2314X_3-0.0001X_4$ and then $R^2$ was 0.8919.

• Korean Journal of Food Science and Technology
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• v.43 no.6
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• pp.719-722
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• 2011

The Daecha-12 and Yabukita varieties of powdered green teas were grown under 85% shade-cultivated condition, and their physicochemical properties were analyzed. Total catechin content was not significantly different but, non-gallated catechin content in Daecha-12 was significantly higher than that in Yabukita. Theanine (32%), caffeine (14%), lutein (15%) and total chlorophyll (28%) levels were significantly higher in Daecha-12 than those in Yabukita. The results of a color analysis showed that the lightness L-value of Yabukita was higher than that of Daecha-12 but, that the greenness negative a-value and b-values of Daecha-12 were higher than those of Yabukita. The Daecha-12 cultivar had lower catechin content but higher content of theanine, caffeine, theobromine, lutein, chlorophyll, and a negative a-value than those of the Yabukita cultivar. Thus, the Daecha-12 cultivar is suitable to prepare a high-quality powdered green tea product.

• KSBB Journal
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• v.23 no.5
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• pp.387-391
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• 2008

Green tea is popular plants in Asian countries and has become more widespread in western countries due to its taste characteristics and health benefits. Apart from green tea leafs, however, the use of root and seed of green tea tree has not intensively been investigated yet. In this study, the contents of mineral, vitamin, total amino acid, free amino acid, and total polyphenol (catechin, caffeic acid, and chlorogenic acid) of the root and seed of green tea tree were analyzed for the development of healthy foods. For minerals, potassium contents were 1,052 and 1,480 mg/100g-dry weight of root and seed, respectively. The order of mineral contents were as follows: K > P > Ca > Mg > Na > Fe > Mn > Zn > Cu in root and K > P > Na > Ca > Mg > Mn > Fe > Cu > Zn in seed. For vitamins, vitamin C contents were 5.72 and 6.05 mg/100g-dry weight of root and seed, respectively. The presence of more various kinds of vitamins were observed in seed than in root. For total amino acids, the contents were 1,651 and 4,335 mg/100g-dry weight of root and seed, respectively. The total amino acid contents of seed and root were higher than those in commercial green tea products. Especially the phenylalanine contents were 16 and 139 mg/100g-dry weight of root and seed, respectively whereas phenylalanine was not found in commercial green tea products. Concerning free amino acids, the bitter tasting amino acids such as arginine, valine and tryptophan were more abundant in root and the sweet tasting ones such as glutamic acid, alanine, aspartic acid, and serine were more abundant in seed. The total polyphenol contents were 237 and 81 mg/100g-dry weight of root and seed, respectively. The polyphenol contents in root were three times higher than that in seed so root may be a better source for antioxidant ingredients than seed. Among many polyphenols, catechin, caffeic acid, and chlorogenic acid were the top three major components.