Effect of Proanthocyanidins on Yeast Metabolism, H + -ATPase Activity, and Wine Fermentation

Proanthocyanidins are extracted from grapes during red wine fermentation. The aim of this study was to understand the effect of proanthocyanidins on yeast metabolism, plasma membrane H⁺-ATPase, and wine fermentation. Two strains of Saccharomyces cerevisiae (industrial strain AWRI R2 and newly selected strain BH8) and a simple model fermentation system containing different concentrations of proanthocyanidins were used. The proanthocyanidins inhibited the activity of H⁺-ATPase during the initial phase of the fermentation, parallel to a decrease in cell growth, CO₂ release, sugar consumption, and ethanol production. However, proanthocyanidins increased in the metabolism of cells and the activity of plasma membrane H⁺-ATPase at the mid-exponential phase. The period of fermentation was shortened by adding proanthocyanidins. In addition, yeast cells preincubated in YPD medium containing proanthocyanidins before inoculation in fermentation medium exhibited weaker inhibition during the initial phase of the fermentation, which may be among the mechanisms of the adaptive response to proanthocyanidins in yeasts. Results suggested that fermentation could be controlled by manipulating proanthocyanidin supplementation.