Abstract
Belgian ale fermentation often relies on complex yeast activity that produces fruity esters, phenolic notes, alcohol-derived warmth, and layered sensory character. This study investigates mixed yeast culture performance in Belgian ale fermentation. Controlled fermentations were conducted using single-strain and mixed-culture yeast treatments under identical wort composition, pitching rate, oxygenation, and temperature conditions. Fermentation rate, attenuation, yeast viability, ester concentration, phenolic compound development, higher alcohol formation, pH change, and sensory aroma balance were measured. The results show that mixed yeast cultures produced broader aroma complexity than single-strain fermentations, mainly through increased ester diversity and moderate phenolic expression. However, strain imbalance caused inconsistent attenuation and stronger variation in final flavour profile. Stable performance was achieved when culture ratio and fermentation temperature were carefully controlled. The study demonstrates that mixed yeast cultures can improve Belgian ale complexity, but microbial dominance and metabolic contribution must be managed for consistent production quality.