Benzie I F, Szeto Y T
Department of Nursing and Health Sciences, The Hong Kong Polytechnic University, Kowloon, Hong Kong SAR.
J Agric Food Chem. 1999 Feb;47(2):633-6. doi: 10.1021/jf9807768.
This study aimed to compare in vitro antioxidant power of different types of tea (Camellia sinensis). The ferric reducing/antioxidant power (FRAP) assay was used to measure the total antioxidant power of freshly prepared infusions of 25 types of teas. Results showed that different teas had widely different in vitro antioxidant power and that the antioxidant capacity was strongly correlated (r = 0. 956) with the total phenolics content of the tea. Expressed as micromol of antioxidant power/g of dried tea leaves, values ranged as 132-654 micromol/g for black ("fermented") teas, 233-532 micromol/g for Oolong ("semifermented") teas, and 272-1144 micromol/g for green ("nonfermented") teas. One cup of tea of usual strength (1-2%), therefore, can provide the same potential for improving antioxidant status as around 150 mg of pure ascorbic acid (vitamin C).
本研究旨在比较不同种类茶叶（茶树）的体外抗氧化能力。采用铁还原/抗氧化能力（FRAP）测定法来测量25种新制茶叶浸出液的总抗氧化能力。结果表明，不同茶叶的体外抗氧化能力差异很大，且抗氧化能力与茶叶中的总酚含量密切相关（r = 0.956）。以每克干茶叶的抗氧化能力微摩尔数表示，红茶（“发酵”茶）的值范围为132 - 654微摩尔/克，乌龙茶（“半发酵”茶）为233 - 532微摩尔/克，绿茶（“未发酵”茶）为272 - 1144微摩尔/克。因此，一杯普通浓度（1 - 2%）的茶提供的改善抗氧化状态的潜力与约150毫克纯抗坏血酸（维生素C）相当。
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