New Insights into the Origin of Volatile Sulfur Compounds during Wine Fermentation and Their Evolution during Aging

Abstract

Volatile sulfur compounds (VSCs) are associated with unpleasant reductive aromas and are responsible for an important reduction in wine quality, causing major economic losses. Understanding the origin of these compounds in wine remains a challenge, as their formation and further evolution during winemaking can involve both chemical and biological reactions. Comparing the VSCs profile (i) of fermenting synthetic grape juices supplemented with a selected VSC (eight compounds tested) and incubated in presence or absence of yeast, and (ii) during storage of wines under an accelerated aging procedure, allowed us to elucidate the chemical and metabolic connections between VSCs during fermentation and aging. Yeast metabolism, through the Ehrlich pathway and acetylation reactions, makes an important contribution to the formation of compounds such as methionol, 3-methylthiopropionate, 3-methylthiopropylacetate, 3-mercaptopropanol, 2-mercaptoethanol and thioesters. By contrast, chemical reactions are responsible for interconversions between thiols and disulfides, the formation of thiols from thioesters or, more surprisingly, the formation of ethylthiopropanol from methionol during fermentation. During aging, variations in heavy VSC concentrations, such as an increase in 3-methylthiopropylacetate and a decrease in ethyl-3-methylthiopropionate formation, were evidenced. Overall, this study highlights that it is essential to consider both yeast metabolism and the high chemical reactivity of VSCs to understand their formation and evolution during winemaking.

Hydrogen sulfide production during early yeast fermentation correlates with volatile sulfur compound biogenesis but not thiol release

“…The association of ETA with H 2 S production during fermentation was previously suggested (Kinzurik et al 2016 ), whereas a recent study reveals that ETA rapidly decreases in the presence of yeast cells (Jiménez-Lorenzo et al 2022 ). Our data, however, could not establish a positive correlation between H 2 S and ETA.…”

“…2-ME is proposed to be the production of cysteine Ehrlich degradation (Silva Ferreira et al 2003 , Vermeulen et al 2006 ). Although a range of reports has accounted for its quantification in distinct wine varieties and beer (Rapp et al 1985 , Vermeulen et al 2006 , Fedrizzi et al 2007 , Jiménez-Lorenzo et al 2022 ), the association of 2-ME and early H 2 S is documented for the first time. The early formation of 2-ME, much like DMDS, could be explained by the vigorous yeast metabolism during the immediate-early stage of fermentation, which may exhibit distinct profiles in finished or aging wines, as the decrease of 2-ME concentration over time invariably shown in previous investigations (Silva Ferreira et al 2003 , Fedrizzi et al 2007 ).…”