Abstract
Non-Saccharomyces yeasts are increasingly studied in specialty beer fermentation because they can introduce distinctive aroma compounds, moderate alcohol formation, improve acidity balance, and support product differentiation. This study examines selected non-Saccharomyces yeasts as functional starter cultures in specialty beer production. Controlled wort fermentations were conducted using single-culture and sequential inoculation approaches, with conventional Saccharomyces cerevisiae fermentation used as the reference. Fermentation rate, sugar consumption, ethanol production, organic acid formation, ester development, phenolic expression, yeast viability, and sensory quality were evaluated. The results show that non-Saccharomyces starters enhanced fruity and floral aroma complexity but showed limited attenuation when used alone. Sequential inoculation improved fermentation completion while preserving aroma diversity. Excessive dominance of non-Saccharomyces strains increased residual sugar and altered flavour balance. The study demonstrates that these yeasts can be used effectively when strain selection, inoculation timing, and fermentation control are carefully managed.