The increase in gluten-related diseases has caused the need to produce gluten-free beers. One way to produce gluten-free beers is to use gluten-free raw materials such as buckwheat and millet, but these require brewing yeast strains adapted to the new substrate. In this master's thesis we investigated how effectively different yeast strains use buckwheat and millet wort, compared to barley wort, and whether the finished products have a satisfactory organoleptic profile. We used four different Saccharomyces pastorianus strains and two Saccharomyces spp. strains, isolated from cider. During fermentation, kinetics and fermentation rate were determined gravimetrically. All strains were most successful in utilisation of barley wort, whereas millet and buckwheat worts were utilised with a similar efficiency. The highest fermentation rates were obtained in the barley wort and the lowest in the millet wort. Using the HPLC method we determined the concentrations of non-utilised sugars, ethanol and glycerol present in the green beer. In all worts, S. pastorianus strains consumed more sugars and produced more ethanol than the strains isolated from cider. Most ethanol was produced in the barley wort, while concentrations were similar between the millet and the buckwheat worts. We also used GC-MS analysis to determine the type and quantity of aromatic compounds produced in green beer. We found that the strains in the barley beer produced more aromatic compounds than in the other two beers, and the concentrations of these compounds were the highest in the barley beer and the lowest in the millet beer.
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