The popularity of non-alcoholic beers has been increasing over the past few years. Maltose-negative strains of different genera are frequently used to obtain beers of low alcohol content. S. cerevisiae hybrids with other Saccharomyces species offer interesting inherited flavour characteristics; however, their use in non-alcoholic beer production is rare. In this work, we constructed six hybrids of maltose-negative S. cerevisiae parental strains (modified to produce higher amounts of organic acids) and S. mikatae (wild-type). Growth behaviour, osmotolerance and fermentation features of the offspring were compared with parental strains. One hybrid with mitochondrial DNA inherited from both parents was used to produce non-alcoholic beer in which organic metabolites were evaluated by HPLC and HS-SPME-GC-MS. This hybrid produced non-alcoholic beer (≤0.05% (v/v)) with an increased organic acid content, just as its parent S. cerevisiae, but without producing increased amounts of acetic acid. The beer had a neutral aromatic profile with no negative off-flavours, similar to the beer produced by the parent S. mikatae, which was used for the first time to produce non-alcoholic beer. Overall, both parents and hybrid yeast produced non-alcoholic beers with increased amounts of higher alcohols compared with esters.

Non-Saccharomyces yeast strains Saccharomycodes ludwigii, Schizosaccharomyces pombe, Lachancea fermentati and Pichia angusta together with a hybrid yeast strain cross-bred between genetically modified Saccharomyces cerevisiae W303-1A G418^R and Saccharomyces eubayanus as well as the parent yeasts of the hybrid were studied for potential use for non-alcoholic beer production. The hybrid yeast, its Saccharomyces cerevisiae W303-1A G418^R parent and Saccharomycodes ludwigii were not able to metabolise maltose during Durham tube tests. Schizosaccharomyces pombe, Lachancea fermentati and Pichia angusta metabolised maltose, however, showed limited ethanol production. Parameters, volatile and non-volatile organic compounds of beers produced by the studied yeast were analysed and compared to a beer produced by bottom fermented brewer’s yeast Saccharomyces pastorianus.

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.

Práca porovnáva obsah prchavých sírnych zlúčenín v slovenských pivách. Sú to látky s výraznou senzorickou charakteristikou a nízkym prahom detekcie, preto môžu arómu piva ovplyvniť negatívne už v stopových množstvách. V pive bolo identifikované veľké množstvo týchto látok, medzi najvýznamnejšie patria dimetylsulfid, dimetyldisulfid, dimetyltrisulfid, etántiol, etyltioacetát, metántiol, metionol, metyltioacetát, 3-metyltiopropylacetát a sírouhlík. V prvom kroku sa optimalizovali podmienky adsorpcie na SPME vlákno-teplota adsorpcie, čas adsorpcie, objem vzorky a prídavok solí, následne sa meral obsah prchavých sírnych zlúčenín v pive plynovou chromatografiou s plameňovým fotometrickým detektorom (GC-FPD) po mikroextrakcii na tuhú fázu (SPME). Boli použité dva vnútorné štandardy-etylmetylsulfid a 1-propyltioacetát. Zistili sa rozdiely v zastúpení jednotlivých zlúčenín v pivách rôznych značiek aj rozdiely medzi pivami s rôznou stupňovitosťou.

Due to their low dead volumes, microcolumns with Tenax TA coupled to a capillary column in the modified GC inlet allow analysis of a broad range of compounds (from acetaldehyde to 2-phenylethanol) in a single sample run. In this study, a micro-column was filled with 10 mg of Tenax TA. Chromatograms showed well-resolved peaks even at the beginning of the run. Static headspace was used to pre-concentrate the compounds. The method is rapid, simple and inexpensive.

The development of innovative non-alcoholic beer (NAB) with health benefits, with the use of 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 characterized 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 positive phenolic off-flavour phenotype. Two strains, K. lactis and K. marxianus, showed strong ß-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). Analysis of volatile organic compound profiles revealed the potential of these yeasts to produce higher alcohols and esters valuable from a brewer’s perspective. Sensorial evaluation of prepared NAB produced with potential probiotic non-Saccharomyces yeasts revealed floral and clove-like aroma traces. 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.