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

Although beer fermentation has traditionally been carried out with <i>Saccharomyces</i>, the boom in craft brewing has led to the use of non-conventional yeast species for beer production. This group also includes non-<i>Saccharomyces</i> starters, which are commonly used in winemaking and which have different technological characteristics compared to standard representatives of the <i>Saccharomyces</i> genus. One of the important characteristics of the non-<i>Saccharomyces</i> group is the richer enzyme profile, which leads to the production of beverages with different taste and aroma profiles. The aim of this study was to investigate sweet and hopped wort fermentation with seven strains of active dry non-conventional yeasts of <i>Lachancea</i> spp., <i>Metschnikowia</i> spp., <i>Torulaspora</i> spp. and a mixed culture of <i>Saccharomyces cerevisiae</i> and <i>Torulaspora delbrueckii</i>. One ale and one lager active dry yeast strain were used as 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 were investigated. The results indicated that all of the studied types of non-conventional yeasts have serious potential for use in beer production in order to obtain new beer styles. For the purposes of this study, statistical methods, principle component analysis (PCA) and correlation analysis were used, thus establishing the difference in the fermentation kinetics of the growth in the studied species in sweet and hopped wort. It was found that hopping had a significant influence on the fermentation kinetics of some of the species, which was probably due to the inhibitory effect of the iso-alpha-acids of hops. Directions for future research with the studied yeast species in beer production are presented.