Abstract
Higher alcohol formation in specialty beers is strongly influenced by fermentation temperature, yeast growth rate, wort composition, and nitrogen metabolism. This study examines fermentation temperature control as a strategy for reducing excessive higher alcohol formation in specialty beer production. Controlled fermentations were performed using selected specialty wort systems under low, moderate, rising, and fluctuating temperature profiles. Higher alcohols, esters, ethanol concentration, attenuation, yeast viability, amino nitrogen uptake, pH change, fermentation duration, and sensory balance were evaluated. The results show that elevated and fluctuating temperatures increased isoamyl alcohol and propanol formation due to intensified yeast metabolic activity. Stable moderate temperature control reduced harsh alcohol notes while maintaining acceptable ester production and fermentation completion. Very low temperatures lowered higher alcohol formation but slowed attenuation and reduced aroma expression. The study demonstrates that temperature control must balance flavour cleanliness with fermentation efficiency. Controlled thermal profiles improve specialty beer smoothness, aroma balance, and product consistency.