Effect of tannic acid on in vitro enzymatic hydrolysis of some protein sources

This study was aimed at determining the effects of selenium on the contents of vitamin C, amino acid, total water-soluble solids and tea polyphenol, and whether the antioxidant activity of selenium-enriched green tea is enhanced compared with regular green tea by linoleic acid oxidation and the lard oxidation method. The contents of selenium, vitamin C and tea polyphenol in green teas were greatly increased by foliar application of selenium-enriched fertilizer. No significant differences of the contents of vitamin C, amino acid and tea polyphenol were observed between green tea treated with sodium selenite and that without selenium. The selenium-enriched green tea exhibited significantly higher antioxidant activity than regular green tea, both in linoleic acid oxidation and in the lard oxidation system. These results suggest that the antioxidant activity of green tea is significantly enhanced by the combination of selenium and green tea constituents compared with that of regular green tea.