Evaluation of the antioxidant activity of red wines in relatinship to their phenolic content

The antioxidant activity of 20 red wines was measured by two in vitro assays: the inhibition of coupled oxidation of beta-carotene/linoleic acid mixture and the free radical scavenger activity using DPPH. Total phenolics, total flavonoids and total anthocyanins of wines were determined spectrophotometrically; individual phenolic compounds were also determined by HPLC. The antioxidant activity of the wines was correlated to their phenolic composition: correlation models showed that the antioxidant activity was related to the total phenolics and total flavonoids by a non-linear correlation. Non-significant correlations were found between the antioxidant activity and total anthocyanidins or individual phenolic compounds. The correlation model was the same when young or one-year-old wines were considered, showing that relatively short storage time under reducing conditions does not substantially modify the antioxidant activity of the phenolic pool.