The Discovery of Disulfides Linked to “Flint” Aroma Formation in Wine

'Flint' aroma is sought after in premium Chardonnay wines. Phenylmethanethiol (PMT) and 2-furanmethanethiol (2-FMT) are known contributors to 'flint' aroma; however, the formation of these compounds in wine is not fully understood. In this study, a novel class of compounds that contribute to 'flint' aroma postbottling was identified in Chardonnay wine. Glutathione and cysteine bound disulfide conjugates of PMT and 2-FMT were proposed as precursors to PMT and 2-FMT, respectively, and an SPE-LC-MS/MS method was developed for the quantification of these disulfides in wine. These compounds were shown to form in the fermentation media, and their concentration negatively correlated with the increase in sulfhydryl concentration as wine aged, suggesting the disulfides liberate PMT and 2-FMT postbottling and contribute to increases of aroma-active thiols. This pathway may contribute to the liberation of PMT alongside other chemical formation pathways that facilitate PMT release during wine aging.