Changes in Polyphenolic Content and Antioxidant Activity of Grapes cv Vranac During Ripening

This study characterised and evaluated the phenolic composition and antioxidant activity of the redwine grape Vranac (Vitis vinifera L.) from the southern Serbian vineyard region during grape ripening.Polyphenol composition at different harvest dates was determined by HPLC-DAD analysis. Antioxidantactivity was estimated by DPPH assay. The study demonstrates that the Vranac variety representsimportant sources of dietary antioxidants. The results show that (+)-catechin, (-)-epicatechin andprocyanidin dimer B2 were the most prevalent in the seeds, and quercetin and malvidin glucosides in thegrape skins. All grape extracts were shown to have high radical-scavenging activity. Strong correlationsbetween radical-scavenging activity and polyphenols suggest that the phenolic composition of the Vranacvariety contributes significantly to the antioxidant capacities of grape extracts. During grape ripeningthere were significant changes in physiological properties and phenolic content, and it is important todetermine optimal harvest time, which will ensure grapes with very good quality parameters (in our studyat the 30th day after véraison)