Monitoring a mixed starter of Hanseniaspora vineae-Saccharomyces cerevisiae in natural must: impact on 2-phenylethyl acetate production.

The effect of simultaneous or sequential inoculation of Hanseniaspora vineae CECT 1471 and Saccharomyces cerevisiae T73 in non-sterile must on 2-phenylethyl acetate production has been examined. In both treatments tested, no significant differences in Saccharomyces yeast growth were found, whereas non-Saccharomyces yeast growth was significantly different during all days of fermentation. Independently of the type of inoculation, S. cerevisiae was the predominant species from day 3 till the end of the fermentation. The dynamics of indigenous and inoculated yeast populations showed H. vineae to be the predominant non-Saccharomyces species at the beginning of fermentation in sequentially inoculated wines, whereas the simultaneous inoculation of S. cerevisiae did not permit any non-Saccharomyces species to become predominant. Differences found in non-Saccharomyces yeast growth in both fermentations influenced the analytical profiles of final wines and specifically 2-phenylethyl acetate concentration which was two-fold increased in sequentially inoculated wines in comparison to those co-inoculated. In conclusion we have shown that H. vineae inoculated as part of a sequential mixed starter is able to compete with native yeasts present in non-sterile must and modify the wine aroma profile.

Increasing the levels of 2-phenylethyl acetate in wine through the use of a mixed culture of Hanseniaspora osmophila and Saccharomyces cerevisiae.

The impact of mixed cultures of Hanseniaspora osmophila and Saccharomyces cerevisiae with different initial yeast ratios on wine composition has been examined. The mixed culture significantly affected sugar consumption, the main enological parameters and ester concentrations, with the exception of glycerol, isoamyl acetate and diethyl succinate levels. Remarkably, in wines obtained with mixed cultures the concentration of 2-phenylethyl acetate was approximately 3- to 9-fold greater than that produced by S. cerevisiae pure culture. Moreover sensory evaluation revealed a stronger fruity character in wines fermented with mixed cultures than in control wines. Independently of the mixed culture used, all wines showed concentrations of acetic acid and ethyl acetate within the ranges described for wines. Our data suggest that a mixed culture of H. osmophila and S. cerevisiae can be used as a tool to increase 2-phenylethyl acetate in wine and that its concentration can be controlled by modulating the initial yeast ratio in the culture.