Anthocyanin adsorption by Saccharomyces cerevisiae during wine fermentation is associated to the loss of yeast cell wall/membrane integrity

Abstract

Yeasts contribute to anthocyanin extraction during red wine fermentation, but they also reduce wine color by adsorption of pigments on their cell walls. Saccharomyces cerevisiae strains vary on their pigment adsorptive properties, but the mechanisms involved in this phenomenon remain unclear. In this work, we evaluated high, medium and low pigment-adsorbing S. cerevisiae winemaking strains during red wine fermentation. Flow cytometry protocols were devised to measure different populations of yeast and their pigment adsorption in association with other variables such as fermentation rate, cell viability, and cell wall/membrane integrity. The results showed that the high pigment adsorbing strain accumulated anthocyanin towards the end of alcoholic fermentation observed as an increase in the population of fluorescent cells. By contrast, low adsorbing strain displayed a single low adsorbing cell population. Pigment adsorption was negatively correlated with cell viability and cell wall/membrane integrity. Independent of their adsorptive potential during wine fermentation, viable cells displayed a low capacity to adsorb anthocyanins, while permeabilized yeast cells exhibited high pigment adsorption capacity. Our findings suggest that yeast pigment adsorption requires a breach to the inner part of the cell wall, for pigments to access constitutively expressed pigment-binding factors, and that the phenotypic differences among strains are determined by their fermentative live-span and cell wall/membrane integrity. These findings will help to rationalize and optimize the match of winemaking strains and vines.