Abstract
To gain knowledge on the role of Saccharomyces cerevisiae yeast strains (and their hybrids) on wine sensory properties, 10 commercially available yeast strains were selected on the basis of their widespread usage and/or novel properties and used to produce Shiraz wines. Significant differences were evident post-alcoholic fermentation and after 24 months of ageing with regards to the number of wine compositional variables, in particular the concentration of tannin and polysaccharide. Strain L2323 is known for its pectinolytic activity and yielded the highest concentration of both yeast- and grape-derived polysaccharides. Wines made with the mannoprotein-producing strain Uvaferm HPS (high levels of polysaccharides) did not have elevated concentrations of yeast-derived polysaccharides, despite this observation being made for corresponding model fermentations, suggesting that mannoprotein production or retention might be limited by the wine matrix. Wine tannin concentration showed a high level of variability between strains, with L2323 having the highest, and AWRI1503 the lowest concentration. Sensory analysis of the wines after 24 months ageing revealed significant differences between the yeast strains, but only the attributes opacity (visual colour) and astringency could be predicted by partial least squares regression using the wine compositional data. Notably, the astringency attribute was associated with higher concentrations of both tannin and polysaccharide, contrary to reports in the literature which suggested that polysaccharide exerts a moderating effect on astringency. The results confirm previous reports demonstrating that the choice of yeast strain represents an opportunity to shape wine style outcomes.
Highlights
It is common practice for winemakers to choose specific Saccharomyces cerevisiae wine yeasts to achieve desired wine styles, as evidenced by the growing number of strains commercially available for use across the global wine industry
Temperatures within fermenters changed over time due to the exothermic nature of alcoholic fermentation, peaking at day 5 for all strains, except 1503, which peaked at day 6
Our study aimed to explore the range of tannin and colour differences achievable from a given grape source by S. cerevisiae strain selection and sought to identify potential mechanisms by which the strains exert these effects
Summary
It is common practice for winemakers to choose specific Saccharomyces cerevisiae wine yeasts to achieve desired wine styles, as evidenced by the growing number of strains commercially available for use across the global wine industry. Key traits described as important for wine yeasts include low production of sulfides and volatile acidity, an optimal flavour profile, the effective use of nitrogen, temperature and ethanol tolerance [2,3,4,5]. Biomolecules 2019, 9, 466 outcomes are most commonly cited in the context of white wine production, from both a sensory and consumer perception perspective [3,6,7]. The perception of ‘quality’ or ‘style’ in red wines is significantly more complex, and it is notable that multiple styles can exist which may have equal success in terms of consumer outcomes [8,9]
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