Yeast-yeast interactions revealed by aromatic profile analysis of Sauvignon Blanc wine fermented by single or co-culture of non-Saccharomyces and Saccharomyces yeasts
This scientific article was realized in collaboration with Pr Hervé Alexandre of the UMR PAM University of Burgundy-AgroSup Dijon.
There has been increasing interest in the use of selected non-Saccharomyces yeasts in co-culture withSaccharomyces cerevisiae. The main reason is that the multistarter fermentation process is thought to simulate indigenous fermentation, thus increasing wine aroma complexity while avoiding the risks linked to natural fermentation. However, multistarter fermentation is characterised by complex and largely unknown interactions between yeasts. Consequently the resulting wine quality is rather unpredictable. In order to better understand the interactions that take place between non-Saccharomyces and Saccharomyces yeasts during alcoholic fermentation, we analysed the volatile profiles of several mono-culture and co-cultures. Candida zemplinina, Torulaspora delbrueckii and Metschnikowia pulcherrima were used to conduct fermentations either in mono-culture or in co-culture with Saccharomyces cerevisiae. Up to 48 volatile compounds belonging to different chemical families were quantified. For the first time, we show that Candida zemplinina is a strong producer of terpenes and lactones. We demonstrate by means of multivariate analysis that different interactions exist between the co-cultures studied. We observed a synergistic effect on aromatic compound production when Metschnikowia pulcherrima was in co-culturewith Saccharomyces cerevisiae. However a negative interaction was observed between Candida zemplinina and Saccharomyces cerevisiae, which resulted in a decrease in terpene and lactone content. These interactions are independent of biomass production. The aromatic profiles of Torulaspora delbrueckii and Saccharomyces cerevisiae in mono-culture and in co-culture are very close, and are biomass-dependent, reflecting a neutral interaction. This study reveals that a whole family of compounds could be altered by such interactions. These results suggest that the entire metabolic pathway is affected by these interactions.