Carbohydrate metabolism in wine yeasts

Abstract

The predominant feature in wine-making is the conversion of sugars contained in grape mashes or musts into ethanol, a task almost exclusively fulfilled by unicellular eukaryotes which divide by budding-the yeasts. Whereas several non-Saccharomyces yeast species are present in the early stages of fermentation, Saccharomyces cerevisiae commonly added in starter cultures generally outgrows all other yeasts in the process of vinification and determines the principle quality of the final product. In the first part of this chapter we recapitulate the pathway of alcoholic fermentation, with special focus on the physiological properties relevant in vinification and the molecular differences discovered between laboratory strains of S. cerevisiae and their relatives employed in wine production. We present the current view on how hexose transport and hexose phosphorylation are especially adapted to the environments encountered during wine production. The generation of organoleptic important by-products of alcoholic fermentation, such as glycerol and acetate, are also discussed. Finally, the three major signaling pathways governing the response to sugar availability, SNF1, cAMP/Ras, and Snf3-Rgt1/2, are briefly explained with relation to wine yeast. An outlook on the growing importance of non-Saccharomyces yeasts and the expected impact of modern high-throughput techniques concludes this review. © Springer International Publishing AG 2017.