Impact of environmental conditions in vscs production during wine fermentation by Saccharomyces cerevisiae

Abstract

The aroma of wine is one of the most important determinants of quality as it strongly influences the consumer’s acceptance or rejection. Among the thousands of molecules comprising the wine aroma, sulfur-containing compounds can be considered as a “double-edged sword”: some of them, deriving from varietal precursors provide fruity pleasant aromas, while other ones, produced by yeast metabolism are related to “unpleasant” aromas. The negative impact and their low limit threshold make these volatile sulfur compounds (VSCs) an essential object of study to control the quality of the wine. To date, the chemical and metabolism mechanisms involved in the formation of VSC during fermentation remain poorly elucidated. Furthermore, the incidence of environmental or technological factors that may interact with yeast metabolism on the VSCs production has not been comprehensively studied. In this context, this project aimed to further investigate the formation of VSCs during S. cerevisiae wine fermentation, assessing the relative contribution of yeast metabolism and chemical conversions to VSCs production and studying the modulation of these productions by environmental (nitrogen resource composition and availability, vitamin concentration) or technological (SO2 addition) parameters. Fermentations were carried out using different conditions (YAN, pantothenic acid concentrations, methionine, and cysteine availability) with 4 S. cerevisiae strains and the production of 18 VACs was measured by GC-MS to elucidated how the variation of these parameters changes final concentration. As expected the addition of methionine incremented the final production of methional derivated compounds but didn’t affect the rest of the compounds. The addition of cysteine increment the production of the esters (methyl thioacetate and ethyl thioacetate) without changing the rest concentrations of other compounds. We also found out that an increment in pantothenic acid, as the addition of methionine, can promote the production of methional-derived compounds. With these data, we could be able to reduced total VSC production during fermentation.