ORAC-fluorescein as a model for evaluating antioxidant activity of wines.

Abstract

In this paper an ORAC-fluorescein (ORAC-FL) protocol for evaluating antioxidant activity of wines has been developed. Fluorescein and radical initiator (AAPH) concentrations were fixed in 70 nmol/L and 12 mmol/L, respectively. Wine concentration that gave a linear response antioxidant activity versus concentration was in the range 0.50-2.0 μL of wine/mL of reaction mixture for white wines, 0.15-0.65 for rose wines, and 0.033-0.20 for red wines. The method was applied to 33 Spanish white, rose, young red, bottled-aged red and oak-aged red wines from different vintages. ORAC-FL values were higher for oak-aged red wines (35.8-63.8 μmol of Trolox equivalent/mL of wine), followed by young and bottled-aged red wines (30.8-40.7), rose wines (8.95-11.2) and white wines (3.18-4.84). Grape variety as well as vintage influenced wine antioxidant activity.