Impact of oenological antioxidant substances on the formation of 1-hydroxyethyl radical and phenolic composition in SO2 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. The phenolic composition of wines was analyzed by high-performance liquid chromatography-diode array detection/electrospray ionization mass spectrometry, antioxidant activity was determined by DPPH (1,1-diphenyl-2-picrylhydrazyl radical) and ABTS [2,2 '-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) radical cation] 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 compared to 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. Wines elaborated with stem extract had a lower concentration of flavonols and stilbenes. CONCLUSION Chitosan and inactive dry yeast, which are used as an alternative to SO2 in winemaking, allow the control of the formation of 1-HER in red wines. Wines with stem and shoot extracts showed a lower resistance to oxidation. (c) 2020 Society of Chemical Industry