Antioxidant activity of wines and relation with their polyphenolic composition

Abstract

The purposes of this work comprise the assessment of the antioxidant activity of wine samples by different analytical methods. The relation between antioxidant values and phenolic composition is also considered as well as the insight of which red wine phenolic fraction is more effective towards quenching radicals. In vitro antioxidant activity of wines has been examined by a number of assays including: oxygen radical absorbance capacity (ORAC), 2,2′-azinobis-(3-ethylbenzothiazoline)-6 sulfonic acid (ABTS) and 1,1-diphenyl-2-picrylhydrazyl (DPPH). Forty-one wine samples were analysed (16 red, 17 white and 9 sherry wines). The total phenolic index was evaluated. In addition, red wines were fractionated using solid phase extraction to separate three main fractions (phenolic acids, flavan-3-ol and anthocyanins, flavonols). Antioxidant activity of red wines is higher than that of white or sherry wines with every method under study. Analysis of variance (ANOVA) demonstrated significative differences among red and white wines; and among red and sherry wines. However, ANOVA showed no statistical significative differences among antioxidant results for white and Sherry wines. Total phenolic content is related to antioxidant activity, the highest correlation coefficients being obtained for ORAC method. Concerning red wine’s fractions activity, larger values were obtained for Fraction 2 corresponding to flavanols and anthocyanins in every case analysed. Additionally, similar values were obtained for Fraction 1 and white wines’ ORAC results.