Abstract
Fermentation temperature profiles strongly affect craft ale quality because temperature controls yeast growth, ester formation, higher alcohol production, attenuation, and flavour stability during storage. This study examines the relationship between fermentation temperature profiles and flavour stability in craft ale production. Controlled ale fermentations were conducted using constant, rising, and fluctuating temperature profiles under identical wort composition, pitching rate, oxygenation, and yeast strain conditions. Fermentation rate, ethanol formation, attenuation, ester concentration, higher alcohols, pH change, dissolved oxygen, aldehyde reduction, and sensory stability during storage were measured. The results show that stable moderate temperature profiles produced balanced ester formation and cleaner flavour persistence. Fluctuating profiles increased fermentation variability and produced higher levels of stress-related aroma compounds. Rising temperature profiles improved attenuation but required careful control to avoid excessive alcohol-derived notes. The study demonstrates that craft ale flavour stability depends on consistent temperature management throughout fermentation and early maturation.