Bioprospecting of <i>Metschnikowia pulcherrima</i> Strains, Isolated from a Vineyard Ecosystem, as Novel Starter Cultures for Craft Beer Production

Abstract

Several studies in recent years have shown that the use of non-Saccharomyces yeasts, used both in single and in mixed fermentations with Saccharomyces cerevisiae, can help produce craft beers with distinctive compositional characteristics. The aim of this study was to evaluate the suitability of three Metschnikowia pulcherrima strains, isolated from Albanian vineyards, for use as starters in the brewing process. Because of its specific enzymatic activities (protease, β-glucosidase, and β-lyase) and its low production of hydrogen sulfide, M. pulcherrima 62 was selected as a starter culture for the production of craft beer. Specifically, the suitability of this yeast for use in sequential inoculation with S. cerevisiae S0-4 for the production of an American IPA-style beer and the main volatile compounds produced during fermentation were evaluated. The results show significant differences in the glycerol, isoamyl alcohol, and isoamyl acetate contents in beer obtained by sequential inoculum of M. pulcherrima 62 with S. cerevisiae S0-4 compared to beer obtained using S. cerevisiae S0-4 as a single starter. Therefore, these preliminary data support the candidacy of M. pulcherrima 62 as a new starter in the brewing process.

Keywords

• craft beer
• <i>Metschnikowia pulcherrima</i>
• <i>Saccharomyces cerevisiae</i>
• sequential inoculation