Abstract
Malt-derived nitrogen fractions influence yeast growth, enzyme activity, amino acid availability, flavour development, and wort fermentability during brewing. This study investigates the effect of malt nitrogen composition on wort fermentability. Malt samples with different modification levels and nitrogen profiles were mashed under controlled temperature and liquor-to-grist conditions. Free amino nitrogen, soluble protein, peptide fractions, maltose release, maltotriose formation, wort viscosity, extract yield, yeast growth, attenuation limit, and fermentation rate were evaluated. The results show that adequate free amino nitrogen improved yeast metabolism and supported efficient sugar utilization. Low nitrogen availability reduced fermentation speed and increased residual extract, while excessive soluble protein increased haze risk without improving fermentability proportionally. Moderately modified malt produced the best balance between nitrogen availability, sugar conversion, and wort clarity. The study demonstrates that wort fermentability depends not only on fermentable sugar concentration but also on the quality and availability of malt-derived nitrogen fractions.