Mixed Cultures of Hanseniaspora vineae and Saccharomyces cerevisiae: Nutrient Effects on Growth, Fermentation, and Wine Aroma Profile

Background and goals The use of a mixed culture of Saccharomyces cerevisiae and non-Saccharomyces yeasts is useful for increasing sensory complexity of wines. Among apiculate yeasts, Hanseniaspora vineae in particular has been used successfully at winery scale and is now available to winemakers as an active dry yeast. This species only tolerates moderate levels of ethanol (similar to 10% v/v). The implementation of a mixed culture with S. cerevisiae is a useful strategy to obtain complete fermentations, with the challenge of maintaining the increase in flavor complexity. Some mixed culture fermentations have been unsuccessful due to nutrient competition; addition of diammonium salts can resolve such unsuccessful fermentations, but diammonium phosphate salt inhibits the production of aroma compounds by H. vineae and other yeasts. Therefore, alternative nutrients and different S. cerevisiae strain partners should be investigated for mixed culture fermentations. Methods and key findings This work focused on the effects of nutrient addition on selected commercial S. cerevisiae strains capable of growing and fermenting with H. vineae (HV205) to improve mixed culture performance. H. vineae fermentations produced higher concentrations of 2-phenylethanol, tyrosol, and tryptophol acetates, compared with pure cultures of S. cerevisiae. These compounds, along with ethyl lactate, 3-methyl-1-butanol, methionol, acetoin, mevalonolactone, gamma-butyrolactone, and C4/C5 isoacids, are produced at significant levels by H. vineae and could be considered as the volatile footprint flavor of this species under mixed culture conditions. This work analyzed the use of appropriate nutrients and S. cerevisiae partners that may influence expected aroma profiles. Conclusions and significance A significant increase in fruity and floral aroma was found in wines produced with mixed culture fermentations than with conventional single-strain S. cerevisiae fermentations (p < 0.005). Growth of the mixed culture was improved by amino acid supplementation compared with yeast extract and commercial yeast lysate, but fermentation kinetics and final aromas were similar in wines with the three S. cerevisiae partners and all the alternative nutrients tested.