Cell wall polysaccharides released during the alcoholic fermentation by Schizosaccharomyces pombe and S. japonicus: quantification and characterization

Yeasts belonging to the genus Schizosaccharomyces have been proposed for use in wine fermentation because of their ability to metabolize malic acid, permitting non-bacterial biological deacidification and averting production of amines. However, Schizosaccharomyces yeasts are associated with the presence of off-characters when left too long in the wine after malo-alcoholic fermentation. To overcome this problem, cells of S. pombe were immobilized in calcium alginate, used in mixed fermentation with Saccharomyces yeasts, and removed once the desired malic concentration was achieved. Non-Saccharomyces yeast confer other benefits such as the release of polysaccharides that can improve wine quality. A previous screen of Schizosaccharomyces strains with different malic acid consumption patterns identified those with high polysaccharide release. A strain of Schizosaccharomyces japonicus showed the greatest polysaccharide release. Here, we evaluated the release of polysaccharide during alcoholic fermentation by an immobilized version of that strain. A commercial strain of S. cerevisiae was inoculated simultaneously and sequentially (after 48 hours) with immobilized cells of S. japonicus. The high release of polysaccharide by the immobilized Schizosaccharomyces strain was confirmed. The greatest polysaccharide release was observed in the sequential trials. The influence of the inoculation mode on the interactions between the two yeast strains and on the analytical profiles of the final wines was also evaluated. Our findings suggest that immobilized cells of S. japonicus not only reduce acidity, but also increase the concentration of active polysaccharide, with beneficial effects for the wine.