Cell Wall Polysaccharides Release during the Alcoholic Fermentation by Schizosaccharomyces pombe

The addition of commercial products containing polysaccharides derived from yeast cell walls to wine is becoming a common practice during the winemaking process. The reduction in protein and tartrate instability, improvement of mouthfeel, increasing sweetness and roundness, decreases in astringency, prevention of tannin aggregation and precipitation, addition of complexity and aromatic persistence, stabilization of the color of red wines, and stability of the foam of sparkling wine have been reported as positive enological properties associated with polysaccharides use. An interesting alternative to the addition of these commercial exogenous polysaccharide-based products could be the use of yeasts able to release high quantities of these compounds during the alcoholic fermentation. Recent results have shown that non-Saccharomyces yeasts are generally characterized by the capacity to release high quantities of polysaccharides. However, few studies have considered the release of polysaccharides by Schizosaccharomyces pombe, a yeast also found in wine production. S. pombe strains have found application in winemaking mainly because of their ability to reduce malic acid in grape juice and/or wine. We evaluated the ability of six different yeast strains of S. pombe to release polysaccharides during the alcoholic fermentation. Interestingly, at the end of the alcoholic fermentation, all of the S. pombe strains released a quantity of polysaccharides three to four times higher than that released by a commercial Saccharomyces yeast strain under the same fermentative conditions of synthetic juice. Polysaccharides released during the alcoholic fermentation were analyzed using a combination of analytical techniques for carbohydrate composition, protein profile, and degree of polymerization of released N-glycans.