The yeast Saccharomyces cerevisiae var. boulardii as a starter culture in wheat beer technology

One of the directions for the development of new products with a unique organoleptic profile is the search and usage of previously unused yeast cultures in brewing. The yeast Saccharomyces cerevisiae var. boulardii is of particular interest both in brewing and food biotechnology in general due to its relatedness to industrial yeast strains of the Saccharomyces cerevisiae species, as well as its distinctive property – probiotic activity. In this work, it was shown that the yeast Saccharomyces cerevisiae var. boulardii Y-3925 can be successfully used in wheat beer technology as a starter culture. It was found that this yeast culture has a number of technologically significant differences from the control strain Saccharomyces cerevisiae W-68, including relatively low enzymatic, flocculation, and biosynthetic activity. Thus, during the main fermentation with Saccharomyces cerevisiae var. boulardii Y-3925, a relatively low fermentation rate and final digestion rate of 3.23±0.63%-mass/day and 52.42±2.00% were observed, respectively (in the case of the control strain W-68, the fermentation rate was 4.70±0.43%-mass/day and final digestion rate was 63.44±1.16%). Low final degree of digestion resulted in a lower concentration of ethyl alcohol, which indicates that this yeast can be used for the production of beer with a reduced ethanol content (low-alcohol beer). The flocculation activity of Saccharomyces cerevisiae var. boulardii Y-3925, determined by the Helm method, was only 6.04±0.96%, which allows this culture to be classified as a weakly flocculating yeast. In terms of biosynthesis of flavour compounds (secondary metabolites), strain Y-3925 is inferior to the control, which can be regarded as a positive technologically significant property in the case of undesirable flavour compounds such as acetaldehyde, diacetyl and higher alcohols. The results obtained in this work can be used as a starting point for the introduction of the yeast Saccharomyces cerevisiae var. boulardii as a starter culture in brewing.