The impact of the physiological condition of the pitching yeast on beer flavour stability:: an industrial approach

Studies on the investigation of the impact of the physiological condition of the pitching yeast on beer flavour stability are reported. Fermentation trials were conducted at industrial scale using a commercial lager brewing yeast at different physiological states. Fermentation performance was followed by monitoring yeast growth, ethanol synthesis, original gravity and attenuation throughout the fermentative process. Beer flavour was evaluated through the content of higher alcohols and volatile esters. After an extended storage, beers were evaluated by an expert sensory panel and the concentration of 2-furaldehyde and E-2-nonenal was assessed. The results demonstrate that the parameters under study are little affected by the physiological condition of the pitched yeast, except for the cell growth which is higher for the yeast pitched with lower vitality. Additionally, a recovery of the yeast vitality is observed at the end of fermentation. A marked improvement on the beer flavour stability can be achieved by increasing vitality of the pitching yeast, according to the statistically significant (t-test, p < 0.1) differences observed in the sensory evaluation. (C) 2003 Elsevier Ltd. All rights reserved.