Yeast Interactions with Anthocyanins during Red Wine Fermentation

The capacity of yeast to modify anthocyanin concentration during red wine fermentation was studied with the objective of classifying yeast strains according to their capacity for color removal during vinification. A model red grape juice medium was used to better understand yeast-anthocyanin interactions. An anthocyanin extract of Vitis vinifera cv. Tannat was prepared from grape skins and diluted in a white must in order to obtain a red grape juice without solids. Anthocyanin removal was confirmed to be higher for compounds with higher polarity. Acylated anthocyanins (acetyl and p-coumaryl compounds) were differentially removed, and the percentage of removal for each compound was determined. Results showed no correlation between color intensity and total anthocyanin concentration after fermentation, possibly because of the presence of anthocyanin derivatives formed during the process. HPLC-MS analysis allowed identification of anthocyanin derivatives, while the quantification of several derivatives was performed by HPLC-DAD. The sum of these derivatives showed a direct correlation with the color intensity obtained with each strain, thus explaining the color variability observed.