Same Yeast, Different Wines: Impact of Different Grape Variety Must Composition on Fermentation Dynamics and Wine Composition

Polyphenols are major quality determinants in red wines, yet their reciprocal impact on yeast metabolism during alcoholic fermentation remains poorly characterized, particularly in natural grapes. This study investigated 32 red Vitis vinifera and hybrid cultivars to evaluate how polyphenolic diversity affects the fermentative behavior of Saccharomyces cerevisiae. Grape polyphenols, especially anthocyanins and tannins, were characterized at macroscopic and microscopic scales, and fermentations were conducted using a standardized microvinification protocol. Fermentative performance was assessed via the maximum CO2 production rate (Vmax). Tannins exhibited a negative correlation with yeast fermentative capacity, independent of their degree of polymerization. Anthocyanins showed structure-dependent effects, with diglucosylated anthocyanins─typical of some hybrid cultivars─displaying the strongest negative correlation with Vmax. However, central carbon metabolism and aroma compound synthesis were mainly driven by must composition (sugar, acidity, and nitrogen). Analysis of grape skin cell wall polysaccharides suggests that pectins may modulate polyphenol extraction and, consequently, yeast fermentation dynamics.