Bioprospecting of Metsnikowia pulcherrima Strains, Isolated from the Vineyard Ecosystem, as Novel Starter Cultures for Craft Beer Production

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, to be used as starters in the brewing process. Due to 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 aptitude of this yeast to be used in sequential inoculation with S. cerevisiae S04 for the production of an American IPA-style beer and the main volatile compounds produced during fermentation were evaluated. Results showed significant differences in glycerol, isoamyl alcohol and isoamyl acetate content in beer obtained with sequential inoculum of M. pulcherrima 62 with S. cerevisiae S04 compared to beer obtained using S. cerevisiae S04 as a single starter. Therefore, these preliminary data support a candidacy of M. pulcherrima 62 as a new starter in the brewing process.