Kinetic Studies on the Ability of Wines to Produce Hydrogen Sulfide (H2S) and Methanethiol (MeSH).

Twelve wines have been stored in anoxia to monitor hydrogen sulfide (H2S) and methanethiol (MeSH) emitted. Emissions were studied for 3 months at 75 °C, 10 months at 50 °C, and 18 months at 35 °C. H2S emissions followed first-order kinetics with half-lives of 0.89 months at 75 °C and (estimated) 24.6 and 160 months at 50 and 35 °C, respectively. Total H2S precursors ([P]0), calculated due to the exhaustion observed at 75 °C, amount to between 1.4 and 2.96 mg/L of H2S. [P]0 correlated with the brine-releasable H2S accumulated by the wines in accelerated reductive aging (AR). MeSH emissions hardly decreased and at 75 °C were between 0.36 and 0.82 mg/L, exceeding the decrease in free methionine (0.26 mg/L on average). MeSH emissions determine MeSH accumulation in AR, far less effectively in red wines, suggesting reactions with polyphenols. MeSH emissions negatively correlated with [P]0, suggesting that these play a key role in regulating redox chemistry during wine aging.