PHENOLIC CONTENT AND ATIOXIDANT ACTIVITY OF RED GRAPES FROM INTERNATIONAL, LOCAL AND HYBRID GRAPEVINE VARIETIES GROWN IN CENTRAL NORTHERN BULGARIA

Abstract

A study to determine the phenolic content and antioxidant activity of grapes from red international (Cabernet Sauvignon), local (Gamza) and hybrid (Rubin) grapevine varieties grown in the region of Central Northern Bulgaria was conducted. The phenolic content of the grapes, the phenolic content and antioxidant activity of their must were determined. Rubin shown the best content of Total Phenolic Compounds (TPC), Flavonoid Phenolic Compounds (FPC), Non-Flavonoid Phenolic Compounds (NPC) and anthocyanins in the structural elements of the cluster. This hybrid variety also shown the highest content of TPC in the must (0.74±0.00 g/l), followed by Gamza, and the lowest TPC was found in the Cabernet Sauvignon – control variety (0.25±0.00 g/l). The highest amount of anthocyanins was found in Rubin grape must (19.91±0.48 mg/l). The dynamics of increasing of the anthocyanin content in the must of the studied varieties followed the order international variety (Cabernet Sauvignon) < local variety (Gamza) < hybrid variety (Rubin). In the red varieties, the grape must of the Rubin hybrid shown significant and the highest antioxidant activity of the three studied varieties. It was four times higher than that found in the Cabernet Sauvignon control. A correlation between TPC, anthocyanin content and antioxidant activity in Rubin was found. This proved the close connection between the phenolic composition and the antioxidant capacity of the variety. The study proved that the grape must of the two studied hybrid and local varieties shown high biological potential and activities.