• 동아시아식생활학회지
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• 제21권2호
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• pp.243-249
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• 2011

This study investigated the physiological and antioxidant activities of green, oolong, and black tea extracts. The crude catechin extract yields of green, oolong, and black tea were 4.9%, 3.4%, and 2.5%, respectively. Total phenol contents of green, oolong, and black tea were 40.9%, 43.0%, and 38.5%, respectively. The order of the electron donating abilities of green, oolong and black tea were green tea>oolong tea>black tea extracts. The SOD-like activities of green, oolong and black tea extracts at 5,000 ppm were 21.2%, 17.5% and 13.9%, respectively. The nitrite-scavenging abilities of green, oolong and black tea extracts were higher than that of ascorbic acid (p<0.05). Antioxidant activities in soybean oil substrates at 500 ppm were in the order of green tea>oolong tea>black tea${\geq}$BHT (200 ppm). Therefore these results showed that the physiological and antioxidant activities of green tea were better than those of oolong and black tea.

• Journal of Community Nutrition
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• 제8권4호
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• pp.207-213
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• 2006

The present study was conducted to investigate the effect of oolong tea extract on blood glucose level and antioxidant system in diabetic rats. The Sprague-Dawley rats were fed on AIN-76 based experimental diets containing 1 % oolong tea extract for 6 weeks. They were induced to be diabetic by receiving streptozotocin (45mg/kg BW) intramuscularly. Blood glucose, blood and hepatic concentration of vitamins A and E, and antioxidant enzyme activities were measured. Oolong tea extract feeding decreased the plasma glucose in diabetic rats. Dietary supplementation of oolong tea extract did not affect antioxidative enzyme activities such as superoxide dismutase, glutathione peroxidase and catalase in diabetic rats. The plasma level of retinol was increased in diabetic rats by feeding oolong tea extract. Plasma and hepatic levels of ${\alpha}$-tocopherol were higher in diabetic rats fed oolong tea extract. In conclusion, these results suggest that oolong tea extract consumption might reduce the plasma glucose in diabetic rats and protect the oxidative damage from diabetic stress to some extent.

• 한국식품영양과학회지
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• 제24권2호
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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.

• 한국식품영양학회지
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• 제15권4호
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• pp.377-381
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• 2002

시판 녹차, 오룡차 및 홍차에서 추출된 조카테킨 조성 및 이들 카테킨의 2성분 항산화시스템, 3성분 항산화 시스템의 항산화 효과를 조사하고자 하였다. 녹차, 오공차 및 홍차의 조카테킨의 수율은 각각 5.4%,3.5% 및 2.5%이 었다. EGC, EC, EGCg 및 ECg의 4개의 카테킨류가 확인되었으며, EGCg 성분이 가장 많은 함량을 보였다. 녹차, 오룡차 및 홍차의 총 카테킨의 함량은 각각 926.3ug/g, 713.8ug/g 및 318.0ug/g이었다. 녹차, 오룡차 및 홍차 조카테킨 첨가구의 항산화 효과는 오룡차 > 녹차 > 홍차의 순이었다. 녹차, 오룡차 및 홍차 조카테킨(100ppm)에 $\alpha$-tocopherol(50ppm)을 첨가했을 때의 항산화효과는 녹차 > 오룡차 > 홍차 조카테킨 순으로 녹차에서 가장 강한 상승작용을 나타냈다. 녹차, 오룡차 및 홍차 카테킨(100ppm)에 $\alpha$-tocopherol(50ppm) 및 ascorbyl palmitate(50ppm)를 함께 첨가한 경우, 조카테킨(200 ppm)을 단독으로 첨가한 경우보다 항산화 효과가 강하였다.

• 한국식품영양학회지
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• 제28권5호
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• pp.766-773
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• 2015

This study analyzes the chemical composition of green tea, white tea, yellow tea, oolong tea and black tea with respect to extraction temperature and time. The optimum extraction conditions for these teas were determined by assessing the chemical composition of tea brewed at different temperature (50, 60, 70, $80^{\circ}C$) and extraction times (1, 3, 5, 10 minute). Catechins contents were the largest at 5 minutes and generally declined by 10 minutes. Green tea catechins contents were highest when brewed at $70^{\circ}C$ and besides other teas a change of the trend variation at 70 and $80^{\circ}C$. These temperatures did not extract theaflavins in green tea. Extract temperature and time did not significantly affect theaflavins content of white tea, yellow tea, and oolong tea. Black tea, however, was noticeably dependent on extract conditions, which were most effective at $70^{\circ}C$, brewed for 5 minutes. Caffeine content of green tea, yellow tea, and oolong tea was highest at 5 minutes, but temperature did not appear to affect the content. White tea and black tea caffeine content was highest when brewed at $70^{\circ}C$ for 5 minutes. Theobromine content of green tea, yellow tea, oolong tea, and black tea did not show major differences between the study times or temperature, though the content in white tea increased with higher temperatures when brewed for 5 minutes. The extraction of phenolic compounds increased until 5 minutes, and showed not further increase at 10 minutes. Antioxidant capacity of green tea, white tea, and yellow tea were maximized at $70^{\circ}C$ for 5 minutes or $80^{\circ}C$ for 3 minutes, while oolong and black tea were reached maximum antioxidants at $70^{\circ}C$ for 5 minutes. In general, to optimize the beneficial chemical content of brewed tea, a water temperature of $70^{\circ}C$ for 5 minutes is recommended.

• 한국식품영양과학회지
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• 제24권2호
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• pp.293-298
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• 1995

Antimicrobial effect of tea extracts from green tea(steamed, roasted), oolong tea and black tea was investigated. Minimal inhibitory concentration(MIC) of tea extraxcts against 9 well known strains of foodborne pathogenic bacteria such as the Gram positive and Gram negative bacteria was determined at 37$^{\circ}C$. Significant antimicrobial activity was observed in the steamed green tea and the roasted green tea of the water-soluble fraciton, and the steamed green tea of the methanol-soluble fraction, and the steamed green tea, roasted green tea and the oolong tea of the crude catechin fraction. The MIC of these extracts against B. subtillis were 700$\mu\textrm{g}$/ml, 500$\mu\textrm{g}$/ml and 120 $\mu\textrm{g}$/ml, respectively. The crude catechin fraction possessed greater antimicrobial activity than did the other fractions. Among tea extracts, extracts of steamed green tea, roasted green tea and oolong tea showed higher antimicrobial activity than them of black tea. The MIC of the crude catechin fraction obtained from tea extracts against Gram-positive bacteria such as M. Iuteus, B. subtillis and S. mutans were 30~50$\mu\textrm{g}$/ml, 120~240$\mu\textrm{g}$/ml and 120~180$\mu\textrm{g}$/ml, and against Gram-negative bacteri such as e. aerogenes and V. parahaemolyticus were 50~60$\mu\textrm{g}$/ml and 60~70$\mu\textrm{g}$/ml in the broth medium, respectively. Especially, the MIC to Streptococcus mutans which has known as a causative bacteria of a decayed tooth were 120$\mu\textrm{g}$/ml, 140$\mu\textrm{g}$/ml, 180$\mu\textrm{g}$/ml and above 1,000$\mu\textrm{g}$/ml in steamed green tea, roasted green tea, oolong tea and black tea, respectively. Tea extracts had strong growth inhibition activity against foodborne pathogenic and dental bacteria.

• 동아시아식생활학회지
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• 제22권4호
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• pp.480-488
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• 2012

Polyphenols may be primarily responsible for the health benefits associated with tea consumption. However, the benefits of the tea polyphenols to bone health have not been studied well. The purpose of this study was to investigate the effects of Oolong tea on bone mineral density and bone-related markers in ovariectomized rats. Sprague-Dawley female rats were randomly assigned to Sham-Control, Sham-Oolongtea, Ovx-Control, and Ovx-Oolongtea groups. Bone mineral density (BMD) and bone mineral content (BMC) were estimated by using PIXImus (GE Lunar Co, Wisconsin.) in the spine and femur. After 6 weeks of the experimental diets, body weight gain, food intake, and food efficiency ratio (FER) were significantly higher in Ovx groups than in Sham groups regardless of diet. The serum concentration of calcium, phosphorus, ALP, and calcitonin were not significantly different according to Oolong tea supplementation. There were no significant differences in urinary calcium and phosphorus excretion between all groups. The urinary DPD crosslinks value was significantly higher in the Ovx-Control group than in the Sham-Oolongtea group. Spine BMD, femur BMD, and spine BMD per body weight were significantly lower in the Ovx groups than in the Sham groups regardless of diet. In the OVX group, spine BMC per body weight, femur BMD per body weight and femur BMC per body weight were significantly higher in the Oolong tea groups than in Control groups. It was concluded that Oolong tea supplementation positively influenced bone health in ovariectomized rats.

• 한국식품영양과학회지
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• 제24권1호
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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.

• 한국식품영양과학회지
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• 제28권3호
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• pp.599-606
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• 1999

Water extracts of persimmon leaf tea(PLTE), green tea(GTE) and oolong tea(OTE), at the con centration used for human consumption, were examined for inhibitory effects on the mutagenicity of major classes of dietary and environmental mutagens including indirect acting mutagens, B[ ]P (benzo[ ]pyrene), IQ(2 amino 3 methylimidazo[4,5 f]quinoline), 2 AA(2 aminoanthracene) in the presence of S9 mix and direct acting mutagen, 4 NQO(4 nitroquinoline 1 oxide) without S9 mix, using the modified Ames Salmonella/microsome assay. PLTE, GTE and OTE showed very potent and concentration dependent antimutagenic effects against indirect acting mutagens B[ ]P and IQ. At the maximum concentration(16,200 g/plate) of each tea extract, number of colonies decreased in a dose dependent manner up to 82~100%. Similar inhibition of PLTE, GTE and OTE were seen at higher concentration in the mutagenicity of the 2 AA following an initial increase in the activity at lower concentration. However, the mutagenicity of the direct acting mutagen 4 NQO were not suppressed at lower concentration of the three tea extracts, and higher concentration of the tea extracts enhanced mutagenic activity of the mutagen. There were no differences in the mode of antimutagenesis between PLTE, GTE, and OTE, in both Salmonella typhimurium TA98 and TA100 strains against the same mutagen. In conclusion, the water extracts of persimmon leaf tea, green tea and oolong tea possess marked antimutagenic potential against a variety of important dietary and environmental indirect acting mutagens, but the activity was not observed against the direct acting mutagens. These results suggest that the mode of inhibitory action may not have resulted from direct interaction between tea extracts and the mutagens, but rather from indirect metabolic inactivation of mutagens by tea extracts.

• 한국식품위생안전성학회지
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• 제13권4호
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• pp.377-382
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• 1998

항산화효과, 항돌연변이효과, 콜레스테롤농도 상승억제작용이 우수한 것으로 알려진 차추출물의 주요성분을 분리 정량하기 위하여 각 발효정도에 따른 분류 및 녹차의 채엽시기별에 따라 녹차 1번차 녹차2번차 녹차 3번차, 우롱차 및 홍차 등에 대한 일반성분, 아미노산, Vit.C, Vit. E, ${\beta}-carotene$, 카테킨류, 카페인, 데오브로마인 및 데오필린 등을 분석하고 특히 항산화성분인 카테킨류의 항산화효과 및 항돌연변이 효과의 연구에 기초자료로 이용하고자 하였다. 녹차 I, II, III, 우롱차 및 홍차의 일반 성분중 조지방함량은 각각 1.1, 2.5, 4.9, 0.8 및 1.2% 이었으며, 총 아미노산함량은 녹차I>녹차II>녹차III의 순이었고 대부분의 아미노산은 차 성분의 유일한 아미노산인 theanine이 차지하였다. 녹차 I, II, III, 우롱차 및 홍차에 함유된 Vit. C함량은 각각 101.6, 87.5, 95.9, 99.1 및 108.0 mg%이었으며, ${\beta}-carotene$ 함량은 각각 270, 268, 481, 80 및 181 ppm이었고, Vit. E 함량은 ${\alpha}-tocopherol$이 대부분을 차지하였으며 ${\beta}-$ 및 ${\delta}-tocopherol$은 모두 검출되지 않았다. 한편, 총카테킨류의 함량은 각각 10.5, 10.4, 7.2, 8.4 및 1.8%로 총카테킨류중 EGCG의 함량이 가장 높았다. 카테킨류 중 EGC의 함량은 녹차I>녹차III>녹차II>우롱차>홍차의 순으로 녹차I이 가장 높았으며, EGCG와 ECG의 함량은 우롱차>녹차I>녹차II>녹차III>홍차의 순으로 우롱차가 가장 높았다. 또한 GA함량은 0.01, 0.02, 0.05, 0.13 및 0.31%로 홍차에 가장 많은 것으로 나타났으며, 카페인 및 데오브로마인 함량도 홍차의 경우가 가장 높았으나 데오필린 함량은 녹차I이 가장 높게 나타났다.