EFFECT OF ETHANOL ON RED WINE TANNIN-PROTEIN (BSA) INTERACTIONS

The interactions between salivary proteins and tannins, responsible fo r the astringency of wine, may reduce phenolic bioavailability. The ef fect of ethanol on protein-tannins interaction and consequently on in- vitro total radical-trapping antioxidant potential (TRAP) of wine was investigated. Scalar amounts of ethanol proportionally reduce the exte nt of tannin precipitation with respect to alcohol-free red wine. This effect is parallel to and has a high correlation (r = 0.978) with the TRAP increase in wine fractions, partially restoring the antioxidant activity lost as a consequence of the interactions with proteins. We p ostulate that ethanol could reduce the chemical interactions between p roteins and red wine tannins. The present work suggests that alcohol s eems to contribute indirectly to the antioxidant capacity of wine by i ncreasing the bioavailability of its phenolic compounds.