• Title, Summary, Keyword: catechins

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Optimal Reaction Conditions and Radical Scavenging Activities for the Bioconversion of Green Tea Using Tannase (Tannase를 이용한 녹차의 생물학적 전환의 최적 조건 마련 및 라디칼 소거능)

  • Hong, Yang-Hee;Yeon, You-Kyung;Jung, Eun-Young;Shin, Kwang-Soon;Yu, Kwang-Won;Kim, Tae-Young;Suh, Hyung-Joo
    • Journal of the Korean Society of Food Science and Nutrition
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    • v.40 no.11
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    • pp.1501-1506
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    • 2011
  • In this study, we optimized the reaction conditions for the bioconversion of green tea using tannase, and to evaluate its radical scavenging activities. Tea catechins such as (-)-epigallocatechin gallate (EGCG) or (-)-epicatechin gallate (ECG) were hydrolyzed by tannase to produce (-)-epigallocatechin (EGC) or (-)-epicatechin (EC), respectively, and a common product, gallic acid. The bioconversion of tea catechins by tannase was increased as enzyme concentration, substrate concentration and incubation time for enzyme dose. The results indicated the optimum reaction conditions for tannase were tannase 30 U/mL (enzyme concentration) on 1% green tea (substrate concentration) for 1 hr (incubation time for enzyme). Tannase enhanced the radical-scavenging properties of green tea; the 2,2-azinobis (3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals scavenging abilities were significantly (p<0.001) greater for the tannase-treated green tea extract compared to the untreated green tea extract. It is reported that ECG has the greatest antioxidant activity among the catechins in green tea, and the release of gallic acid is considered to be beneficial because of its significant antioxidant potency. The results of this study suggest that the tannase-treated green tea increases antioxidant activities under optimum reaction conditions.

Rapid Measure of Color and Catechins Contents in Processed Teas Using NIRS (근적외선 분광광도계를 이용한 차 제품의 색상 및 카테킨류의 신속 측정)

  • Chun, Jong-Un
    • Korean Journal of Plant Resources
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    • v.23 no.4
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    • pp.386-392
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    • 2010
  • This study was done to measure the color and catechins contents in processed teas using the whole bands (400~2500 nm) with near-infrared spectroscopy(NIRS). The powder colors of 109 processed teas were measured with a colorimeter. The a/b ratios in Hunter color scale in processed teas accounted for about 98.9% of the variation in the fermentation degree(FD), indicating that the a/b ratio was a very useful trait for assessing fermentation degree. Also tea powders were scanned in the visible bands used with NIRSystem. The calibration equations for powder colors were developed using the regression method of modified partial least squares(MPLS) with the internal cross validation. The equations had low SECV (standard errors of cross-validation), and high $R^2$ (coefficient of determination in calibration) values with 0.996~1.00, indicating that the visible bands(400~700 nm) with NIRS could be used to rapidly measure the variables related to powder color and fermentation degree. Also another powders of 137 processed teas were scanned at 780~2500 nm bands in the reflectance mode. The calibration equations were developed using the regression method of MPLS with the internal cross validation. The equations had low SECV, and high $R^2$ (0.896~0.983) values, showing that NIRS could be used to rapidly discriminate the contents of EGC($R^2$=0.919), EC(0.896), EGCg(0.978), ECg(0.905) and total catechins(0.983) in processed teas with high precision and ease.

Maturation Effects of Don Tea on Physicochemical Components and Anti-Microbial (돈차(錢茶)의 숙성 기간이 이화학적 성분과 항균 활성에 미치는 영향)

  • Park, Yong-Seo;Ryu, Hyeun-Hee;Lee, Mi-Kyung;Kim, Hyun-Ju;Heo, Buk-Gu
    • Journal of the East Asian Society of Dietary Life
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    • v.19 no.1
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    • pp.32-37
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    • 2009
  • This study was carried out to gather basic data on the restoration and extent of Don tea (a coin-shaped tea), the traditional tea of Korea. We examined the physicochemical components and anti-microbial activity of Don tea extracts at 0, 5 and 10 months. The Hunter value $L^*$, of Don tea extracts which were matured for 10 months decreased from 7.01 to 4.97 compared to that when the extracts were first manufactured. However, the $b^*$ value increased from 0.09 to 2.67. There were higher contents of inorganic matter in Don tea extracts following manufacture in the order of K (14.12 mg/100 mL), Mg (0.94 mg/100 mL), P (0.88 mg/100 mL), Ca (0.16 mg/100 mL) and Mn (0.16 mg/100 mL). Classified catechins contents were found in the order of C (19.97 mg/100 mL), EGC (9.30 mg/100 mL), ECG (9.02 mg/100 mL), GCG (8.50 mg/100 mL), GC (7.61 mg/100 mL) and CG (5.63 mg/100 mL). The longer the maturation period of the Don tea extracts, the lower the contents of inorganic matter and catechins. However, this did not apply to the total phenol contents, particularly in the phenol contents of Don tea extracts matured for 10 months which increased by 93.82 mg/l00 mL. Don tea extracts which were matured for longer periods showed higher anti-microbial activities against Bacillus subtilis and Streptococcus mutans. However, there were lower activities against Staphylococcus aureus, Escherichia coli and Salmonella enteritidis. Consequently, it was concluded that a shorter maturation period was required for the effective utilization of the inorganic matter, the catechins and the gram-negative bacteria in the Don tea extracts. However, a longer maturation period of 10 months was found to effectively utilize the total phenol compound contents and the gram-positive bacteria.

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Effects of Polyphenol and Catechin Levels on Antioxidant Activity of Several Edible Flower Extracts (주요 식용꽃 추출물의 폴리페놀과 카테킨류 함량이 항산화 활성에 미치는 영향)

  • Lee, Mi-Kyung;Park, Jung-Suk;Song, Hee-Ja;Chon, Sang-Uk
    • Korean Journal of Plant Resources
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    • v.27 no.2
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    • pp.111-118
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    • 2014
  • Contents of phenolics, flavonoids, and catechins, and antioxidant activity were investigated in the ethanol extracts of three different flower species, Magnolia denudata, Prunus mume, Carthamus tinctorius. Total phenolics were more present in M. denudata than P. mume or C. tinctorius, ranging from 72.6 to 118.0 mg/kg (p < 0.05). Total flavonoids level had same tendency to total phenolics content, showing highest amount (25.1 mg/kg) in M. denudata. The antioxidant activity of the methanol extracts from all the flowers dose-dependently increased. DPPH free radical scavenging activity at 250 mg/kgwas higher in M. denudata and P. mume by 93.0 and 92.6%, respectively, than C. tinctorius by 23.0% (p < 0.05). Total catechins content including 6 compounds was higher in M. denudate (9,425.5 mg/kg) than that in P. mume or C. tinctorius (3,407.8 or 190.6 mg/kg). However, P. mume extracts showed highest amount in caffeine as well as vitamine C. DPPH radical scavenging activity in three different flowers was highly correlated with contents of total phenolics ($r^2=0.7994$), total flavonoids ($r^2=0.9131$), and total catechins ($r^2=0.5929$), and their content and activities were different depending on species.