Impact of oenological antioxidant substances on the formation of 1-hydroxyethyl radical and phenolic composition in SO 2 free red wines.

BACKGROUND: Different natural substances, chitosan, inactive dry yeasts, and freeze-dried aqueous extracts from two wine industry by-products (stems and shoots) were used in red winemaking as possible alternatives to SO2 . The resistance to oxidation of wines was evaluated by Electron Paramagnetic Resonance (EPR). The phenolic composition of wines was analyzed by HPLC-DAD-ESI-MSn, the antioxidant activity was determined by DPPH and ABTS assays and spectrophotometric measurements of color were compared.

RESULTS: The wines elaborated with chitosan and inactive dry yeast presented greater capacity to inhibit the formation of the 1-hydroxyethyl radical in comparison with the wines elaborated with stem or shoot extracts. The total content of anthocyanins was higher in the wines elaborated with SO2 , however, the concentration of flavan-3-ols was higher in the wines with chitosan. In addition, the wines with chitosan and inactive dry yeast presented the highest % polymerization. While wines elaborated with stem extract had a lower concentration of flavonols and stilbenes.

CONCLUSION: The chitosan and inactive dry yeast, used as an alternative to SO2 in winemaking, allow the control of the formation of 1-HER in red wines. While the wines with stem and shoot extracts showed lower resistance to oxidation. This article is protected by copyright. All rights reserved.