Saccharomyces cerevisiae and Hanseniaspora uvarum mixed starter cultures: influence of microbial/physical interactions on wine characteristics.

The growing trend in the wine industry is the revaluation of the role of non-Saccharomycesyeasts, promoting the use of these yeasts in association withSaccharomyces cerevisiae. Non-Saccharomycesyeasts contribute to improve wine complexity and organoleptic composition. However, the use of mixed starters needs to better understand the effect of the interaction between these species during alcoholic fermentation. The aim of this study is to evaluate the influence of mixed starter cultures, composed by combination of differentS. cerevisiaeandHanseniaspora uvarumstrains, on wine characteristics and to investigate the role of cell-to-cell contact on the metabolites produced during alcoholic fermentation. In the first step, threeH. uvarumand twoS. cerevisiaestrains, previously selected, were tested during mixed fermentations in natural red grape must in order to evaluate yeast population dynamics during inoculated fermentation and influence of mixed starter cultures on wine quality. One selected mixed starter was tested in a double-compartment fermentor in order to compare mixed inoculations ofS. cerevisiae/H. uvarumwith and without physical separation. Our results revealed that physical contact betweenS. cerevisiaeandH. uvarumaffected the viability ofH. uvarumstrain, influencing also the metabolic behaviour of the strains. Although different researches are available on the role of cell-to-cell contact-mediated interactions on cell viability of the strains included in the mixed starter, to our knowledge, very few studies have evaluated the influence of cell-to-cell contact on the chemical characteristics of wine.