Aroma Impact of Ascorbic Acid and Glutathione Additions to Sauvignon blanc at Harvest to Supplement Sulfur Dioxide

Abstract

Higher levels of the varietal thiols 3-mercaptohexanol (3MH) and 3-mercaptohexyl acetate (3MHA) were seen in research-scale Sauvignon blanc wines following applications of 100 mg/kg ascorbic acid or glutathione to machine-harvested juices in addition to a moderate addition of 30 mg/kg sulfur dioxide. Antioxidant effects at the beginning of yeast fermentation were implicated, which can support 3MH formation when oxidative influences are controlled, as monitored through changes in polyphenol content. An increase in 4-mercapto-4-methylpentan-2-one (4MMP) was seen with added glutathione, while similar concentrations of many remaining aroma compounds, including esters, C₆ alcohols and higher alcohols, were seen in the wines regardless of the extra antioxidant additions at harvest.