Antioxidant activity and phenolic composition of organic and conventional grapes and wines

The phenolic compounds and antioxidant activity from Monastrell variety grapes obtained by organic and conventional agriculture during the last month of ripening and the wines obtained from them were studied. Samples of grapes were collected from the last month of ripening to full maturity in each plot, and winemaking was carried out on the day of the final collection of grape samples, coinciding with the maturity of the grapes. The antioxidant activity a month before harvesting was higher in the organic grapes (5.7 +/- 0.03 mM Trolox/g) than in the conventional ones (4.40 +/- 0.05 mM Trolox/g), although these differences disappear in the moment of harvesting. Similarly the total amount of phenolic compounds a month before harvesting was higher in the organic grapes (974.2 +/- 54.4 mg/kg) than in the conventional grapes (447.7 +/- 27.8 mg/kg), although these differences disappear at the moment of harvesting. In wine, phenolic compounds and the antioxidant activity were slightly higher in organic wine than in conventional wine, although the differences were not significant. (C) 2010 Elsevier Inc. All rights reserved.