Effect of soluble polysaccharide addition against oxidation of rosé wines.

Rosé wines, due to lower phenolic compounds and antioxidant content, are especially vulnerable to oxidation. Moreover, the valorization of winemaking byproducts is gaining interest, as it has the potential to reduce the environmental impact of wine production. For these reasons, the aim of this study was to investigate the effect of the addition of soluble polysaccharides, obtained from white grape pomace, on the phenolic oxidation of Syrah rosé wines. The soluble polysaccharides were extracted, characterized and added to the wines, which were periodically saturated with oxygen. The evolution of the phenolic composition and color parameters (CIELAB) was monitored by means of HPLC-DAD-MS and UV-vis spectrophotometry, respectively. The polysaccharide extract was mainly formed by homogalacturonans, type-II rhamnogalacturonans and polysaccharides rich in arabinose and galactose. The addition of this soluble extract seemed to promote the formation of acetaldehyde-mediated derived pigments in rosé wines, with an increase in color intensity and sulfite bleaching resistance. During oxygenation, a protective trend against the degradation of flavanols and phenolic acids was also observed in the polysaccharide-added rosé wines, which exhibited, at the end of this study, concentrations of these compounds that were 43.7 % and 11.5 % higher, respectively, than those in control samples. Therefore, these results suggest a protection of wine polyphenols, which reveals the potential use of these waste-derived extracts as a new oenological adjuvant for enhancing the phenolic and color stability of rosé wines.