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.