Use of vine-shoots stilbene extract to the reduction of SO2 in red and rosé Italian wine: Effect on phenolic, volatile, and sensory profiles.

Sulfur dioxide (SO2) is one of the most used additives in wine industry for its antioxidant and antimicrobial activity. However, due to health concerns, consumers' demand of wines with either reduced or totally replaced SO2 has increased. This study aimed to assess the effect of partial and total replacement of SO2 with a vine-shoots extract rich in stilbenes in rosé (cv. Sangiovese) and red (cv. Negramaro) wines respectively. Color as well as phenolic, volatile, and sensory profiles of wines were evaluated at bottling and during storage. The results showed that the vine-shoots extract increased the levels of trans-resveratrol, catechin, and gallic acid in wines. Moreover, the positive correlation of procyanidin dimers in red wine suggested an increase of the polymerization reactions. The amount of added extract probably provided lower antimicrobial protection compared to SO2, as indicated by the higher levels of ethyl phenol. The decrease of individual anthocyanins and oxidation aldehydes observed in wines with SO2 replacement and the higher levels of caftaric acid in the rosé wine with the extract suggested a shift of the oxidative protection, with a lower protection towards anthocyanin degradation and higher protection towards carbonyl formation and oxidation of readily oxidizable phenolic acids.