• Korean Journal of Food Science and Technology
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• v.37 no.4
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• pp.513-518
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• 2005

Capillary electrophoresis (CE) method was developed to determine (+)-catechin and (-)-epicatechin contents in grape seed ethanol extract. CE separation was achieved using 100 mM phosphate and borate buffer at pH 6.0 as background electrolyte and fused silica capillary with 50 microns x 375 microns O.D. (effective length 20.0cm) maintained at $25^{\circ}C$. The applied voltage was 10kV, and detection was performed by DAD at 210 nm, Two catechins were well separated within 6 min with repeatability of <0.8% RSD for migration time and <2.0% RSD for peak area, and correlation coefficients higher than 0.994 were obtained from 58.0 to 174.0 mg/L with detection limit of 0.035 mg/L. Separated compounds were successfully determined. CE method was easy to handle and showed good reproducibility. CE method was compared with conventional coloring and HPLC methods, and main advantages of CE method were low amount of sample required, simple pre-sample treatment, good recovery rate, and short analysis time.

• Korean Journal of Breeding Science
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• v.41 no.4
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• pp.660-663
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• 2009

The new Camellia sinensis L. variety, "Hankwang" was selected from 630 clones of the tea plant clone garden in Bioenergy Crop Research Center, National Institute of Crop Science (NICS), RDA. This variety was selected to develop superior variety for high productivity and nutrient components from 2004-2008. We evaluated the clones by the characteristics of the leaf, nutrient components, and yield. "Hankwang" was finally selected from six regional trials from 2006-2008. The number of buds and weight of "Hankwang" were better than the control cultivar "Yabukata". "Hankwang" was observed to be more resistant to cold and disease compared to the control. The nutrient components of "Hankwang" such as tannin, catechin, total nitrogen, and caffeine were 16.7, 6.08, 2.32 and 2.00%, respectively.

• Journal of agriculture & life science
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• v.43 no.3
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• pp.27-34
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• 2009

Green tea was prepared by soaking 1.5 g of green tea leaves into 100 mL of distilled water at $75^{\circ}C$ for 5 min. The green tea was stored at three different conditions - (A) green tea was stored at not-artificially excluding natural light condition, at natural air condition, and without addition of vitamin C; (B) green tea was stored at artificially excluding natural light condition by wrapping a vial with aluminium foil, at nitrogen filling up condition, and with addition of 30 mg/100 mL of vitamin C; and (C) green tea was stored at artificially excluding natural light condition by wrapping a vial with aluminium foil, at nitrogen filling up condition, and without addition of vitamin C. After 28 days of storage at $4^{\circ}C$, the chemical quality of the green tea was evaluated. Total phenolic contents of (A), (B), and (C) green tea decreased to 71.50, 73.88 and 75.07%, respectively, after storing for 28 days compared to those of beginning state. DPPH radical scavenging activities of (A), (B), and (C) green tea were 87.87, 92.93 and 88.39%, respectively. Epigallocatechin gallate (EGCG), the main active compounds of green tea, contents of (A), (B), and (C) green tea were 130.61, 136.47 and 4.34%, respectively. The results indicated that light, air condition, and vitamin C were significantly important to the chemical quality of green tea during storage.

• Journal of the Korean Society of Food Science and Nutrition
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• v.31 no.5
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• pp.749-753
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• 2002

The effects of green tea powder (GTP) on the rheological properties of dough and gelatinization characteristics were evaluated by farinograph, extensograph, amylograph and DSC. The flours used were high strength flour (HF: 12.5% protein) and blend of 50% high strength flour and 50% low strength flour (HLF: 10.5% protein). As the amount of GTP increased, water absorption, development time and weakness of the dough decreased for both flours, but dough stability increased only for HLF; the extension of the dough decreased but the resistance to extension increased. The pasting temperature increased and maximum viscosity decreased. On the other hand, with the addition of green tea extract to the wheat starch, transition onset temperature, transition peak temper-ature and enthalpy decreased, demonstrating that catechins in green tea facilitate the starch crystal melting.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2004.04a
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• pp.296-301
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• 2004

We focused our research interests on the characteristic of silk fabrics dyed with green tea extracts and, moreover, revealed the catechin content of silk fabrics after dyeing with Korean tea extract by measuring the residues. Three kinds of green tea samples were taken between April and May, 2003, from Bosung(southern province in South Korea), in different terms as the first corp, the second corp, and the third corp. Before and after dyeing the silk fabrics with these extracts, catechins in the residue were analyzed by HPLC. Four kinds of Catechins, such as (-)-epicatechin(EC), (-)-epicatechin gallate(ECG), (-)-epigallocatechin (EgC), (-)-epigallocatechin gallate(EgCG) were isolated from Korean green tea extracts. Catechine contents in Korean green tea leaves depend on the making process such as heating and steaming, and the younger the richer. The absorbed catechins in sillk fabrics after dyeing followed in a decreasing order of EgCG>EgC>ECG>EC. We have found a 68% uptake of EgCG, and 116.8mg/g of EgCG in the silk fabrics after dyeing with 1% Korean green tea extracts.

• Journal of the Korean Society of Food Science and Nutrition
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• v.33 no.4
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• pp.753-756
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• 2004

The effect of far-infrared (FIR) treatment on total flavanols contents and catechin composition of green tea were determined by vanillin spectroscopic and HPLC methods. Total flavanols content of green tea increased from 145 mg/g to 160 mg/g after FIR treatment for 10 min, but decreased from 146 to 90 mg/g after FIR treatment for 20 min. Among nine catechins of green tea, epicatechin derivatives decreased continuously with treatment time of FIR, while catechin derivatives increased up to 10 min and decreased to 20 min. These results indicate that FIR treatment exerting appreciable influence on catechin content of green tea may be useful as one of processing method improving quality of green tea.

• Journal of Food Hygiene and Safety
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• v.11 no.2
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• pp.83-87
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• 1996

The objective of this study is to investigate the direct effects of green tea catechins(GTC) on vascular smooth muscle tension and 45Ca2+ Uptake in rat aorta. The methods used in this study are isometric tension measurements using physiograph, Lanthanum method for 45Ca2+(2 uCi/ml) uptake measurement in rat aorta. GTC modified tension induced by 40 mM KCl or 1 uM norepinephrine in rat aorta. Low concentrations of GTC(<0.5mg/ml) increased tension by 40 mM KCl or 1 uM norepinephrine, individually. However, high conecentration of GTC(>0.5 mg/ml) inhibiited tension by 40 mM KCl or 1 uM norepinephrine, individually. GTC increased 45Ca uptake induced by 40 mM KCl in a dose-dependent manner. From these results, GTC has the dual actions in vascular smooth muscle in vitro. Low concentrations of GTC augments tension by K or norepinephrine. However, high concentrations of GTC inhibits tension by K or norepinephrine GTC may have Ca2+ channel activation, action, which may result in unphysiological vasodilation by Ca2+ overload in vascular smooth muscle.

• Journal of Korean Society of Water and Wastewater
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• v.28 no.6
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• pp.713-723
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• 2014

Biofouling in brackish water reverse osmosis (RO) membranes still needs extensive research to understand cause and mechanism and to obtain methods for reduction of its impact on RO applications. Natural compounds with biofilm formation inhibitory properties are being investigated. Two compounds, vanillin and Epigallocatechin gallate (EGCG), were selected due to their great potential on biofilm formation inhibition. Vanillin shows inhibition on quorum sensing mechanisms of biofilm formation. EGCG has potential to inactivate microbial activity. The two compounds were incorporated in typical polyamide reverse osmosis membranes and evaluated on flux behaviours and biofilm formation potential. The surface properties of membrane coated with vanillin were changed tremendously compared to those with EGCG. As a result, the flux was reduced substantially. The biofilm formation seems hindered with EGCG coated membranes compared to the virgin membranes. More research is needed to optimize coating methods applicable to RO membranes and to enhance biofouling reduction.

• Food preservation and processing industry
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• v.7 no.2
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• pp.33-36
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• 2008

차는 차나무 잎을 가공한 것으로 녹차 등의 비발효차, 우롱차 등의 반발효차, 홍차 등의 발효차로 분류된다. 우롱차, 홍차 등의 발효는 미생물이 관여하는 발효가 아니고 찻잎에 존재하는 효소에 의한 반응을 이용하므로 효소 발효차로 불리운다. 반발효차는 $10{\sim}65%$ 발효도 그리고 발효차는 85% 이상의 발효도 제품으로 통상 정의되나 발효정도를 판단할 수 있는 기준이 설정되어 있지 않아 발효도 100%에 해당되는 위치를 구명하여 발효차 발효정도 판별 기준으로 활용하고자 발효과정 중 일어나는 성분과 색조의 변화를 검토하였다. 적색도(a 값)와 황색도(b 값)는 위조 및 유념 과정에서부터 색을 띠기 시작하여 발효 진행과 함께 증가하여 발효 시작 일정시간 후 최고점에 도달하고 이후 감소를 보였다. 가시영역의 녹차와 홍차의 스펙트럼에서 가장 큰 차이를 보인 420 nm 흡광도 값은 발효 진행과 함께 증가되어 일정시간 후 최고점에 도달하고 이후 감소를 보였다. 찻잎 성분 중 카테킨류는 5종이 검출되었는데 발효 진행과 함께 모두 급격히 감소하였다. 그러나 카페인은 발효 진행과 관계없이 거의 일정 수준을 유지하여 카페인은 효소 발효에 의해 변환되지 않는 성분으로 확인되었다. 4종의 테아플라빈류는 발효 0%에 해당하는 녹차에는 검출되지 않았으나 발효 진행과 함께 생성됨이 확인되었다. 테아플라빈류는 4종이 검출되었는데 이중 생성량이 많은 것은 TF3,3'G와 TF3G 순이었으며 이 성분들은 발효의 진행과 함께 일정시간 후 최고점에 도달하고 이후 감소를 보였다. 발효차 제조과정 중 발효에 의해 생성되는 적색과 황색 그리고 420 nm의 흡광도 값 그리고 발효에 의해 생성되는 TF3,3'G와 TF3G 생성 최고점에 이르는 발효시간이 일치함이 발견되었다. 이 최고점은 발효도 100%에 해당하는 위치로 판단된다.

• Journal of the Korean Society of Food Science and Nutrition
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• v.21 no.4
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• pp.386-389
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• 1992

The four main tea catechin components (-)-epicatechin (EC), (-)-epigallocatechin (EGC) , (-)-epicatechin gallate (ECg), and (-)-epigallocatechin gallate (EGCg) were analyzed quantitatively from commerical green teas by HPLC. CATechin of the most amounts in steamed and parched teas was EGcg (steamed 1st : 7.54% , parched 1st : 7.88%). Amounts of catechins decreased in the following order : EGCg > EGC>ECg>EC. Almost same tendency of catechin components change of 1st tea and 2nd tea differed to harvesting time being observed in steamed and parched teas. In 2nd tea, amounts of EGCg increased more than in 1st tea. It seems that this change effects on the quality of tea taste.