Non-Saccharomyces Yeasts Nitrogen Source Preferences: Impact on Sequential Fermentation and Wine Volatile Compounds Profile

Abstract

Nitrogen sources in the must are important for yeast metabolism, growth, and performance, and wine volatile compounds profile. Yeast assimilable nitrogen (YAN) deficiencies in grape must are one of the main causes of stuck and sluggish fermentation. The nitrogen requirement of Saccharomyces cerevisiae metabolism has been described in detail. However, the YAN preferences of non-Saccharomyces yeasts remain unknown despite their increasingly widespread use in winemaking. Furthermore, the impact of nitrogen consumption by non-Saccharomyces yeasts on YAN availability, alcoholic performance and volatile compounds production by S. cerevisiae in sequential fermentation has been little studied. With a view to improving the use of non-Saccharomyces yeasts in winemaking, we studied the use of amino acids and ammonium by three strains of non-Saccharomyces yeasts (Starmerella bacillaris, Metschnikowia pulcherrima, and Pichia membranifaciens) in grape juice. We first determined which nitrogen sources were preferentially used by these yeasts in pure cultures at 28 and 20°C (because few data are available). We then carried out sequential fermentations at 20°C with S. cerevisiae, to assess the impact of the non-Saccharomyces yeasts on the availability of assimilable nitrogen for S. cerevisiae. Finally, 22 volatile compounds were quantified in sequential fermentation and their levels compared with those in pure cultures of S. cerevisiae. We report here, for the first time, that non-Saccharomyces yeasts have specific amino-acid consumption profiles. Histidine, methionine, threonine, and tyrosine were not consumed by S. bacillaris, aspartic acid was assimilated very slowly by M. pulcherrima, and glutamine was not assimilated by P. membranifaciens. By contrast, cysteine appeared to be a preferred nitrogen source for all non-Saccharomyces yeasts. In sequential fermentation, these specific profiles of amino-acid consumption by non-Saccharomyces yeasts may account for some of the interactions observed here, such as poorer performances of S. cerevisiae and volatile profile changes.

Effect of the inoculation strategy of non-Saccharomyces yeasts on wine malolactic fermentation

“…The coexistence of the two yeast populations may have resulted in higher nitrogen consumption. This data is in agreement with other studies reporting competition for nitrogen sources between yeasts (Gobert et al, 2017). No significant differences in ammonium consumption by yeasts were observed here.…”

Identification and Characterization of Non-Saccharomyces Species Isolated from Port Wine Spontaneous Fermentations

“…Culture medium containing a yeast nitrogen base supplemented with three essential amino acids (L-proline, L-glutamine, and L-arginine) resulted in severely reduced growth rates of the selected strains. These results are in line with previous reports, explained by the peculiar amino acid consumption requirements of non-Saccharomyces strains [69].…”

Influence of Nutrient Supplementation on Torulaspora Delbrueckii Wine Fermentation Aroma

“…Supplementation with nutrients promotes fermentation activity, with a higher consumption of sugar and higher production of ethanol [38]. Thus, the role of nutrients in the stimulation of fermentation kinetics is confirmed for T. delbrueckii in this experiment.…”