Non-Conventional Yeasts for Beer Production – Primary Screening of Strains

Although the beer fermentation traditionally is carried out with Saccharomyces, the increasing interest in innovative beers lead to the use of uncharacterized autochthonous starter cultures, spontaneous fermentation, or non-Saccharomyces starters, which leads to the production of distinctive and unusual products. Non-Saccharomyces yeasts are generally characterized by low fermentation yields and are more sensitive to ethanol stress, but they provide a distinctive aroma and flavor. The aim of this study was to investigate the sweet and hopped wort fermentation with 7 strains of active dry non-conventional yeasts of the Lachancea spp, Metschnikowia spp., Torulaspora spp. and a mixed culture of Saccharomyces cerevisiae and Torulaspora delbrueckii. One ale and one lager active dry yeast strains were used as a control strains. The extract consumption, ethanol production, degree of fermentation, pH drop, as well as the yeast secondary metabolites formed by the yeast (higher alcohols, esters and aldehydes) in sweet and hopped wort was investigated. The results indicated that all of the studied types of non-conventional yeasts were with serious potential for use in beer production in order to obtain new beer styles.