Changes of contents and antioxidant activities of polyphenols during fruit development of four apple cultivars

Polyphenols are functional components in apples and can be separated into four groups by Sephadex LH-20 as epicatechin, procyanidolic oligomers, chlorogenic acid and procyanidolic polymers. Antioxidant activities of each group were determined by FRAP and DPPH radical scavenging assay. It was found that procyanidolic oligomers and procyanidolic polymers influenced the total polyphenols content (measured by Folin–Ciocalteu method) much more in Jonagold, Golden Delicious, Fuji and Guoguang four apple cultivars. The Fe-reducing activity of procyanidolic oligomers in the four apple cultivars increased significantly during the development while the other three compounds changed irregularly. And the Fe-reducing activities of epicatechin and procyanidin contributed much more to the total Fe-reducing activities during the fruit development in the four apple cultivars. The DPPH scavenging activities of four compounds in Jonagold and Golden Delicious decreased during fruit development and that of Fuji and Guoguang changed irregularly. Chlorogenic acid was the main contributor in Jonagold, Golden Delicious and Fuji to the total scavenging activity. In Guoguang, it was procyanidolic oligomers that contributed much to the total scavenging activity.