• Journal of the Korean Society of Food Science and Nutrition
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• v.24 no.2
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• pp.299-304
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• 1995

Antioxidative effect of tea extracts from green tea(steamed, roasted), oolong tea and black tea was investigated. Antioxidative activities of the crude catechin fraction were the most effective in oolong tea which contained the highest level of (-)-epigallocatechin gallate(EGCg). The water-soluble fraction obtained from oolong tea exhibited binding with more ferrous than copper ions. It showed a synergistic effect when used with an antioxidant such as BHT(0.5mg) and $\alpha$-tocopherol(2mg). Especially, this synergistic effect was exhibited more with BHT than with $\alpha$-tocopherol. Also steamed green tea, roasted green tea and oolong tea showed remarkable free radical scavenging action. The SC50(the concentration of a water-soluble fraction which is required to scavenge 50% of 100$\mu$M 1, 1-diphenyl-2-picryl hydrazyl radicals) of steamed and roasted green tea, oolong tea and black tea extracts were 11.3$\mu\textrm{g}$/ml, 11.4$\mu\textrm{g}$/ml, 12.7 $\mu\textrm{g}$/ml and 14.9$\mu\textrm{g}$/ml, respectively. It is assumed that the antioxidative activity of tea extracts is due to inhibition of peroxidation free radical scavenging and binding action of ferrous ions by mainly tea polyphenol compounds.

• Korean journal of food and cookery science
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• v.21 no.3 s.87
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• pp.346-353
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• 2005

CThis study used HPLC to analyze the contents of 7 kinds of catechins, 4 kinds of theaflavins, and 2 kinds of methylxanthines in the following 6 kinds of commercial Korean tea: 2 green, 2 black, 1 jasmine and loolong. The following ranges in the 13 tea components of the 6 samples by ethanol extract were evaluated in mg/g: (-)-epigallocatechin, 0(black tea and jasmine tea) to 14.19(green tea); (-)-catechin 0; (+)-epicatechin, 0.62(bran rice-green tea) to 2.91(black tea); (-)-epigallocatechin gallate, 4.59(black tea) to 43.96(jasmine tea); (-)-gallocatechin gallate, 0.58(black tea) to 5.80(jasmine tea); (-)-epicatechin gallate, 5.63(bran rice-ueen tea) to 48.06(jasmine tea): (-)-catechin gallate, 0.26(black tea): theaflavif 0 to 3.66(black tea): theaflavin-3-gallate, 0 to 6.94(black tea): theaflavin-3'-gallate, 0 to 4.01(black tea); theaflavin-3,3-digallte, 0 to 10.25(black tea); caffeine, 4.60(bran rice-peen tea) to 26.44(black tea); and theobromine, 0.10(bran rice-green tea) to 1.81(jasmine tea). The contents of all components were lower by water extract than by ethanol extract. Therefore, total catechin (100.55, 45.88 mg/g) and theobromine (1.81, 0.86 mg/g) contents in jasmine tea, and theaflavin content (24.88, 1.36 mg/g) in black tea by ethanol and water extract were the highest. Caffeine content was the highest in black tea(96.48 mg/g) for the ethanol extract, and in jasmine tea (12.38 mg/g) for the water extract.

• Journal of Food Hygiene and Safety
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• v.13 no.4
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• pp.377-382
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• 1998

This study was carried out to measure the contents of moisture, crude ash, crude fat, total amino acid, with amino acid composition, vitamin C, ${\beta}-carotene$, vitamin E, total catechins, EGCG, EGC, ECG, EC, GA, caffeine, theobromine and theophylline of the green tea I, II, III, oolong, and black tea. The content of crude fat of green tea I, II, III, oolong, and black teas was 1.1, 2.5, 4.9, 0.8 and 1.2% respectively, total amino acid content was 0.87, 0.78, 0.60, 0.63 and 1.05% respectively, and theanine content was 0.52, 0.48, 0.31, 0.41 and 0.61%, respectively. Total amino acid content of green tea increased in the order of green tea I> green tea II> green tea III, and among the teas, the content of theanine was the highest in the amino acids present. The content of vitamin C of green teal, II, III, oolong, and black tea was 101.6, 87.5, 95.9, 99.1 and 108.0 mg%, respectively, ${\beta}-carotene$ content was 270, 268, 481, 80 and 181 ppm, respectively. Among the ${\alpha}-,\;{\beta}-,\;{\gamma}-\;and\;{\delta}-tocopherol$, the content of ${\alpha}-tocopherol$ was the highest in vitamin E present, and ${\beta}-\;and\;{\delta}-tocopherol$ were not detected in the samples of green teal, II, III, oolong, and black teas. The total catechins of green teal, II, III, oolong, and black teas was 10.5, 10.4, 7.2, 8.4 and 1.8% respectively, and among them, EGCG content was the highest. The content of EGC increased in the order of green tea I > green tea III > green tea II > oolong tea> black tea. The contents EGCG and ECG increased in the order of oolong tea> green tea I > green tea II> green tea III> black tea, and the highest contents of EGCG and ECG were observed in the samples of oolong tea. The content of GA was 0.01, 0.02, 0.05, 0.13 and 0.31%, respectively, and the highest contents of GA, caffeine and theobromine were observed in the sample of black tea. The highest content of theophylline, however, was observed in the sample of green tea I.

• Journal of Nutrition and Health
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• v.27 no.10
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• pp.1007-1017
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• 1994

In order to investigate the effect of Korean green tea, oolong tea and black tea beverage on the antioxidative detoxification in cadmium(Cd) poisoned rat liver, male Sprague-Dawley rat weighing 143$\pm$3.2g were divided into control and experimental groups. The experimental groups were fed standard diet containing 40ppm Cd and were given distilled water(CD), 5% black tea(BT), oolong tea(OT) and green tea(GT), respectively. Tea beverages were extracted from 5G dry leaves of teas in 100ml hot distilled water by the treatment at 85$^{\circ}C$ for 3 min. Liver xanthine oxidase(XOD) activity was increased by the administration of Cd except GT group. Liver superoxide dismutase(SOD), glutathione peroxidase(GSH-px), glutathione S-transferase(GST) activities were decreased by te administration of Cd but did not decreased by the administration of green tea(in GT group). Vitamin E and reduced glutathione contents were significantly decreased in Cd administered groups. Liver lipid peroxide value in Cd administered groups were increased compared to control group, but was not increased in GT group. Serum glutamic oxaloacetic transaminase(GOT) activities in CD, OT, BT groups were higher than control, but that in GT group was similar to control group. Serum glutamic pyruvic transaminase(GPT) activity was not significantly different among various groups. It was concluded that green tea might alleviate peroxidative damage in Cd-administered rat liver by reinforcing antioxidative detoxification system.

• Journal of the East Asian Society of Dietary Life
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• v.11 no.4
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• pp.305-314
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• 2001

The study was conducted to investigate the effect of added green tea and black tea powder on the quality of bread during storage. Tea bread was prepared with 0.1% and 2% concentration of green tea (GT) and black tea(BT) powder. The crude fat contents of GT 2% group and BT 2% group were significantly higher than those of control group. GT l% group and BT l% group. The loaf weight of the control group was the lowest and its loaf volume was the highest. Especially, GT 2% group had the lowest loaf volume. The internal lightness value of control group was the highest. the redness value of BT 2% group and the yellowness value of GT 2% group were the highest. GT 2% group was significantly higher in hardness and gumminess and BT l% group was higher in cohesiveness and springiness. After 5 day storage, the retrogradation of GT 2% group was the highest and that of BT 2% group was the lowest among groups. After 5 day storage. pH. titratable acidity and total colony count of GT 2% group was the lowest and those of control group was the highest. The sensory score of control, GT l% and GT 2% group were evaluated higher than others. The shelf-life of tea breads were prolonged to 1~3 days by adding green tea powder and black tea powder as compared with the control group. but It must be considered the way to increase the quality of bread in loaf volume and retrogradation.

• Journal of the Korean Society of Food Science and Nutrition
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• v.24 no.1
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• pp.160-168
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• 1995

Desmutagenicities against 2-amino-1-methyl-6-phenylimidazo[4, 5-b] pyridine(PhIP) and 2-amino-3, 8-dimethylimidazo[4, 5-f]quinoxaline(MelQx) of tea extracts (steamed green tea, roasted green tea, oolong tea and black tea) were investigated. All the fractions obtained from tea extracts showed strong desmutagenic activity against PhIP and MeIQx toward S. typhimurium TA 98 in the presence of the S-9 mix. The crude catechin fraction exhibited the strongest desmutagenic activity. Among these tea extracts, black tea especially exhibited the strongest desmutagenic activity and the activity was 70.9~91.0% against PhIP and 92.2~98.8% against MelQx at a concentration(0.5~1.0mg/plate) for drinking. The activity of authentic catechins of (-)-EGC, (-)-EGCg, (-)-ECg and (-)-EC were 79.5%, 60.2%, 46.1% and 43.5% against PhIP, and were 52.3%, 11.6%, 8.2% and 22.1% against MelQx by addition of 1.0mg/plate, respectively. The desmutagenic activity was supposedly due to the (-)-EGCg, (-)-EGC and (-)-EC in tea polyphenols, and the browning materials. The desmutagenicity was stronger when mutagens were preincubated with S-9 mix after reaciton with black tea extracts than when preincubated with them after reaction with S-9 mix. The desmutagenicity of tea extracts was rather expressed by reacting directly with mutagens than by deactivating the activated forms of mutagens.

• Asian-Australasian Journal of Animal Sciences
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• v.27 no.11
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• pp.1571-1576
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• 2014

Nutritive values of green and black tea by-products and anti-nutritive activity of their tannins were evaluated in an in vitro rumen fermentation using various molecular weights of polyethylene glycols (PEG), polyvinyl pyrrolidone (PVP) and polyvinyl polypyrrolidone as tannin-binding agents. Significant improvement in gas production by addition of PEG4000, 6000 and 20000 and PVP was observed only from black tea by-product, but not from green tea by-product. All tannin binding agents increased $NH_3$-N concentration from both green and black tea by-products in the fermentation medium, and the PEG6000 and 20000 showed relatively higher improvement in the $NH_3$-N concentration. The PEG6000 and 20000 also improved in vitro organic matter digestibility and metabolizable energy contents of both tea by-products. It was concluded that high molecular PEG would be suitable to assess the suppressive activity of tannins in tea by-products by in vitro fermentation. Higher responses to gas production and $NH_3$-N concentration from black tea by-product than green tea by-product due to PEG indicate that tannins in black tea by-product could suppress rumen fermentation more strongly than that in green tea by-product.

• Journal of the Korean Society of Food Science and Nutrition
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• v.12 no.2
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• pp.99-104
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• 1983

Chemical changes of major tea constituents by tea manufacture were examined by the quantitative masurements of tannin, caffeine, free sugars and total amino acid. The sample used in this experiments was fresh green and black tea leaves, green tea prepared by classical panning process and black tea prepared by commercial process. The results obtained are as follows: Compared with fresh tea leaves, tannin was increased 2% in green tea and decreased 56.5% in black tea by tea manufacture. Caffeine was increased 25.9% in green tea and decreased 3.1% in black tea. Total free sugars were decreased 78.2% and 76.7% in green tea and black tea, respectively. Total amino acids were decreased 26.1% and 18.8% in green tea and black tea, respectively.

• Journal of Nutrition and Health
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• v.5 no.3
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• pp.109-125
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• 1972

According to the Sam-guk Sa-gi (History of three Kingdoms: Silla, Koguryo and Paeckje) tea was first brought into Korea by Kim Tae-ryeum, a diplomat, in 828 A.D. during the reign of king Hung-dot of Silla, and planted on the hill of Mt. Chi-ri. Afterwards, the tea trees were transplanted and cultivated by Buddists in many Buddist temples in southern provinces during the Silla and Koryo dynasties. People took much delight in drinking green tea, and specially the kings, buddist monks and nobilities of Silla and Koryo enjoyed drinking green tea. And eventually, the green tea became an indispensable part in all important ceremonies during the Koryo dynasty. After the Yi dynasty came into being, the dualistic philosophy of China was introduced and respected while buddist temples declined as a result of strong oppression by the ruling class. While temples were declined, the practice of drinking green tea was also declined. Nowadays we find many tea plants grow wild, which are seemed to be planted around buddist temples during the Koryo dynasty. Today, Korean people do not drink home made green tea. Instead, they like to take coffee, black tea and other tea products imported from foreign countries. Aa a result, Korea had to pay $ 520 thousand in 1969 to import foreign made tea and coffee. The natural conditions of southern provinces of Korea are very suitable in cultivating tea plants. If we develope the skill in producing good quality tea in Korea, we would be able to save the foreign exchanges that are being spent for importing foreign made tea products, and at the same time, we would be able to export our green tea to overseas. The quality of Korean green tea is as good as that of Japanese green tea. Green tea contains vitamin C while coffee and black tea do not contain it.

• Journal of the Korean Society of Food Science and Nutrition
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• v.23 no.5
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• pp.784-791
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• 1994

This study was to investigate the cadmium removal effect of Korean green tea, black tea and oolong tea beverage on Cd administered rat, tissues and their excretions. Male Sprague-Dawley rats weighing 143±3.2g were divided into control and experimental groups. The control group were fed standard diet without cadmium . The experimental groups, which were fed standard diet containing 40 ppm Cd, were divided into 4 subgroups again , which were the groups given distilled water (CD group), 5% black tea (BT group), oolong tea (OT group ) and green tea (GT group), respectively. Five days before to sacrifice the rats, all 4 cadmium fed groups were supplied 1 ml of water with 600ppm Cd and control group were fed 1 ml of distilled water without Cd under the same dietary condition. After that, their excretion were collected separately for 3 days. In rat liver and kidney, accmulation of cadmium in 4 Cd administered groups were more than in control group and that of GT group was significantly less than CD group. In bone , also, accumulation of cadmium in 4 Cd administered groups was more than in control group and that of GT, OT,BT groups were much less than that of CD group. GT group was excreted more Cd in urine than Cd group. In feces, 3 tea feeding groups (BT, OT, GT group) were excreted Cd 1.7, 2.1, 2.4 times more than that of the CD group, respectively. We conclude that cadmium accumulations of GT feeding group in rat's liver, kidney and bone were much less than CD group , and the absorption and retention rate of GT group was significantly lower than CD group.