Antioxidant activity of Malvasia istriana grape juice and wine

The phenolic composition, including hydroxybenzoic acids, hydroxycinnamic acids and flavan-3-ols, was identified and quantified in grape juice and wine produced from cv. Malvasia istriana (Vitis vinifera L.) grafted on two rootstocks, Kober 5BB and 420A, by using high-performance liquid chromatography (HPLC) coupled with diode array detection. Protocatechuic acid, p-coumaric acid, (+)-catechin and (+epicatechin were the major phenols deter mined in the samples. The antioxidant activity of grape juice and wine was measured by the P-carotene bleaching (BCB) and 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging methods. Good correlation was observed between the total phenol content of grape juice and wine and the antioxidant activity measured by the BCB and DPPH methods as well as between the results of both methods.