Time course accumulation of polysulfides in Chardonnay and model juice fermentations

Over the last five years, polysulfides in wine have become a topic of interest. The finding that both yeast and the wine composition could contribute to the formation and evolution of these compounds has prompted several studies, further corroborated by the discovery of a link between polysulfides and H2S release during ageing. In the present study, the accumulation of cysteinylated and glutathionylated polysulfides was followed during fermentation for the first time. Synthetic grape media and Chardonnay juice treated with CuSO4, elemental sulfur or both were fermented, and subsequently analysed using an in-house UHPLC-HRMS method. Differences in polysulfide accumulation were observed between the two media, highlighting the role of the matrix composition. Elemental sulfur, especially when combined with CuSO4, resulted in significantly increased accumulations of polysulfides compared to controls in both media. Polysulfides with longer S-chains generally appeared later in the fermentation, an observation that prompted further questions on these metabolites' formation.