Total antioxidant capacity of teas by the ferric reducing/antioxidant power assay

摘要

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 μmol of antioxidant power/g of dried tea leaves, values ranged as 132-654 μmol/g for black ('fermented') teas, 233-532 μmol/g for Oolong ('semifermented') teas, and 272-1144 μmol/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).