Recently, non-Saccharomyces yeast have become very popular in wine and beer fermentation. Their interesting abilities introduce novel aromatic profiles to the fermented product. In this study, screening of eight non-Saccharomyces yeast (Starmerella bombicola, Lindnera saturnus, Lindnera jadinii, Zygosaccharomyces rouxii, Torulaspora delbrueckii, Pichia kluyveri, Candida pulcherrima, and Saccharomycodes ludwigii) revealed their potential in non-alcoholic beer production. Conditions for non-alcoholic beer production were optimised for all strains tested (except T. delbrueckii) with the best results obtained at temperature 10 to 15 °C for maximum of 10 days. Starmerella bombicola, an important industrial producer of biosurfactants, was used for beer production for the first time and was able to produce non-alcoholic beer even at 20°C after 10 days of fermentation. Aromatic profile of the beer fermented with S. bombicola was neutral with no negative impact on organoleptic properties of the beer. The most interesting organoleptic properties were evaluated in beers fermented with L. jadinii and L. saturnus, which produced banana-flavoured beers with low alcohol content. This work confirmed the suitability of mentioned yeast to produce non-alcoholic beers and could serve as a steppingstone for further investigation.

The development of non-alcoholic beer (NAB) with health benefits, using non-conventional potential probiotic yeasts, offers an interesting alternative to standard NAB brewing strategies. In this study, potential probiotic non-Saccharomyces yeasts Pichia manshurica, Kluyveromyces lactis, and Kluyveromyces marxianus, along with commercial probiotic yeast Saccharomyces boulardii, were characterised and tested for functional NAB production, whereas P. manshurica was used in NAB production for the first time. Growth and viability were assessed across a range of temperatures, pH, and iso-α-bitter acids. The tested yeasts withstood conditions typical of the beer matrix and human digestive tract and had a positive phenolic off-flavour phenotype. Two strains, K. lactis and K. marxianus, showed strong β-glucosidase activity, which may enhance beverage aroma complexity. Ethanol levels in beers fermented with non-Saccharomyces yeasts remained below the NAB limit (≤0.5% v/v). An analysis of volatile organic compound profiles revealed the potential of these yeasts to produce higher alcohols and esters valuable from a brewer’s perspective. This study provides valuable insight into novel probiotic fermentations and the potential application of unconventional yeasts in functional, aromatic, and health-oriented non-alcoholic beverages.

Impact of different pure cultures of Saccharomyces cerevisiae on the volatile profile of Cabernet Sauvignonrosé wines | Tereza Drtilová, Katarína Ďurčanská, Andrea Machyňáková, Ivan Špánik, Tatiana Klempová, Katarína Furdíková | Agricultural Journals

Metschnikowia pulcherrima is one of the most studied non-Saccharomyces yeasts. It is widely used as a biocontrol agent during the initial stages of fermentation. However, its aerobic metabolism has not been fully investigated yet. This work aims to characterize five autochthonous M. pulcherrima strains from a microbiological and technological perspective, taking a closer look at their anaerobic and aerobic metabolism. M. pulcherrima is a low-fermentative yeast with moderate ethanol tolerance, high osmotolerance and high beta-glucosidase production. The presence of oxygen during fermentation experiments resulted in higher glucose consumption and higher ethanol concentration than under anaerobic conditions. Conversely, ethanol yield decreased under aerobic conditions. In terms of winemaking, both the presence of oxygen and the aeration time are important factors. We found that 48 h of aeration led to high glucose consumption and balanced volatile organic compounds (VOC) production. However, longer aeration times can lead to the destruction of the aromatic profile of the wine, particularly due to the high concentrations of fusel alcohols and ethyl acetate. Additionally, 48 h of aeration enriched the aromatic profile through increased concentrations of the desirable compounds 2-phenlyethanol and 2-phenylacetaldehyde.