Abstract
Belgian-style beers are known for complex aroma profiles, and non-Saccharomyces co-fermentation offers a route to increase fruity, floral, acidic, and spicy sensory notes. This study examines non-Saccharomyces co-fermentation for aroma complexity in Belgian-style beers. Controlled fermentations were conducted using selected non-Saccharomyces yeasts together with conventional brewing yeast under fixed wort gravity, pitching rate, oxygenation, and temperature conditions. Fermentation rate, sugar utilization, ethanol formation, ester production, organic acid development, phenolic expression, yeast viability, attenuation, and sensory aroma quality were evaluated. The results show that co-fermentation increased ester diversity and improved aroma depth compared with single-strain fermentation. However, excessive non-Saccharomyces dominance reduced attenuation and increased residual sweetness. Sequential inoculation provided better fermentation completion while preserving aroma complexity. The study demonstrates that Belgian-style beer innovation can benefit from controlled co-fermentation when culture ratio, inoculation timing, and fermentation temperature are carefully managed.