Comprehensive study of the evolution of gas-liquid partitioning of aroma compounds during wine alcoholic fermentation
Résumé
Calculating the gas-liquid partitioning of aromatic molecules during winemaking fermentation is essential to minimize the loss of aroma and to optimize the fermentation conditions. In this study, the effect of the main fermentation parameters on the partition coefficients (k(i)) of higher alcohols (2-methylpropan-1-ol and 3-methyl butan-1-ol) and esters (ethyl acetate, 3-methyl-1-butyl acetate, and 2-ethyl hexanoate) was assessed. The values of k(i) were first determined in synthetic media simulating must and wine. They varied considerably with both the hydrophobicity of the compound and the composition of the medium. Then, the effect of temperature on k(i) was quantified. The absence of any effect of gas composition was also established by replacing air with CO(2). Finally, the impact of CO(2) stripping was assessed by running specific fermentations in which the rate of CO(2) production was kept constant by perfusion with assimilable nitrogen. These fermentations showed that in contrast to temperature and must composition, CO(2) stripping did not change the gas liquid partitioning of higher alcohols and esters.