Liberation of Hydrogen Sulfide from Dicysteinyl Polysulfanes in Model Wine

Diorganopolysulfanes can be generated when hydrogen sulfide (H 2 S) and thiols are oxidized in the presence of Cu(II) under conditions usually aimed at removing H 2 S from wine. This work sought to understand if polysulfanes could act as latent sources of H 2 S during postbottling storage. The stability of the polysulfanes formed in situ in model wine containing cysteine, H 2 S, and transition metals was dependent both on the number of sulfur linking atoms (S n ) and on the presence of a reducing agent, such as sulfur dioxide or ascorbic acid. A polysulfane containing three linking sulfur atoms was the most stable, with 84% of the relative initial amount remaining in solution after six months, compared to polysulfanes containing four or more linking sulfur atoms that decomposed rapidly, with 26% remaining after six months. Importantly, sulfur dioxide was associated with the rapid degradation of polysulfanes and subsequent liberation of H 2 S. Three cysteine- S -sulfonates were also tentatively identified, which gives insight into the possible release mechanisms involved with H 2 S reappearance.