Polysaccharides and glycerol production by non-Saccharomyces wine yeasts

In the last few years the attention of wine industry has been addressed to the research of new and improved wine-yeast strains useful for the production of different types and styles of wines. In this context, several studies report on the advantages deriving from the utilization of non-Saccharomyces yeasts in mixed starter cultures with Saccharomyces cerevisiae (Ciani et al., 2010). In fact, although non-Saccharomyces are often referred as spoilage yeasts, they are also characterized by the production of high glycerol concentrations (Ciani et al., 1996; Romano et al., 1997) and of specific enzymes involved in the release of aromatic compounds (Rosi et al., 1994; Esteve-Zarzoso et al., 1998). Less is known on their contribution to the production of polysaccharides. Since polysaccharides in wine are important to improve mouthfullness, richness and aromatic persistence, to stabilize colour and avoid protein and tartrate instability (Feuillat, 2003), with this study we evaluated the ability of non-Saccharomyces yeasts to produce total polysaccharides during fermentation carried out by pure and mixed cultures with a commercial starter strain of Saccharomyces cerevisiae. Moreover, the effect of non-Saccharomyces yeasts on glycerol production was evaluated in mixed fermentation trials.