Evidence of different fermentation behaviours of two indigenous strains of Saccharomyces cerevisiae and Saccharomyces uvarum isolated from Amarone wine.

Aims: To explain the role of Saccharomyces cerevisiae and Saccharomyces uvarum strains (formerly Saccharomyces bayanus var. uvarum) in wine fermentation. Methods and Results: Indigenous Saccharomyces spp. yeasts were isolated from Amarone wine (Italy) and analysed. Genotypes were correlated to phenotypes: Melibiose) and Melibiose+ strains displayed a karyotype characterized by three and two bands between 225 and 365 kb, respectively. Two strains were identified by karyotype analysis (one as S. cerevisiae and the other as S. uvarum). The technological characterization of these two strains was conducted by microvinifications of Amarone wine. Wines differed by the contents of ethanol, residual sugars, acetic acid, glycerol, total polysaccharides, ethyl acetate, 2-phenylethanol and anthocyanins. Esterase and b-glucosidase activities were assayed on whole cells during fermentation at 13 and 20C. Saccharomyces uvarum displayed higher esterase activity at 13C, while S. cerevisiae displayed higher b-glucosidase activity at both temperatures. Conclusions: The strains differed by important technological and qualitative traits affecting the fermentation kinetics and important aroma components of the wine. Significance and Impact of the Study: The contribution of indigenous strains of S. cerevisiae and S. uvarum to wine fermentation was ascertained under specific winemaking conditions. The use of these strains as starters in a winemaking process could differently modulate the wine sensory characteristics.