Schizosaccharomyces japonicus: A Polysaccharide-Overproducing Yeast to Be Used in Winemaking

Mixed starter cultures made of Saccharomyces cerevisiae EC1118 and Schizosaccharomyces
japonicus #13 were inoculated in commercial grape must, and the impact of different inoculum
ratios (1:1; 1:100; 1:10,000) on growth and fermentation kinetics and on the analytical profiles of
the experimental wines was here evaluated. Results obtained showed that S. japonicus #13 affects
S. cerevisiae growth and fermentative capability only for S. cerevisiae/S. japonicus inoculum ratio
1:10,000. The analytical profiles of the wines produced by mixed starter cultures indicated that this
non-Saccharomyces yeast modulates the concentration of malic and acetic acids and of some of the
most important volatile compounds, such as -phenyl ethanol, in an inoculum-ratio-dependent
fashion. Moreover, all experimental wines obtained with S. japonicus #13 in mixed cultures reached
concentrations of total polysaccharides significantly higher than those obtained with pure cultures
of S. cerevisiae EC1118, and total polysaccharides increased with the increase of S. japonicus #13 cell
concentration. Based on these results, S. japonicus #13 might be profitably inoculated in combination
with S. cerevisiae EC1118 to enhance wine complexity and aroma and to improve wine stability by
increasing the final concentration of polysaccharides.