Schizosaccharomyces japonicus/Saccharomyces cerevisiae mixed starter cultures: New perspectives for the improvement of Sangiovese aroma, taste, and color stability

Schizosaccharomyces japonicus and Saccharomyces cerevisiae were inoculated in Sangiovese grape must and the impact of simultaneous (co-inoculation) and sequential inoculation protocols on growth and fermentation kinetics, and on the analytical and sensory profiles of the experimental wines, was evaluated at the end of the alcoholic fermentation and after aging in bottle. While Sch. japonicus proved to affect S. cerevisiae growth and fermentative performances solely in sequential inoculation, the combined activity of the two yeasts always resulted in significantly higher total polysaccharides concentrations (p < 0.05), no matter the inoculation protocol utilized. Moreover, Sch. japonicus modulated the concentration of some volatile compounds when in mixed culture. In particular, ethyl acetate, that reached high levels at the end of alcoholic fermentation, showed a significant decrease after twenty-four months of bottle aging (p < 0.05), when the occurrence of hydrolysis/esterification reactions led to a significant increase of other acetate esters (p < 0.05). As a result, sensory analyses showed no significant differences for the ethyl acetate perception in mixed fermentation and control aged wines. Moreover, sequentially inoculated wines showed significantly higher sweetness compared to control wines, possibly due to the higher glycerol and polysaccharide content.