Control of selected fermentation indices by statistically designed experiments in industrial scale beer fermentation

摘要

Fermentation indices of a?bottom-fermented lager brew from high gravity wort (15.5?°P) were analysed using the?response surface methodology (RSM, Box-Behnken design). Fermentation parameters like pitching rates (6–10?mln?cells?mL –1 ), wort aeration (8–12?mg?O2?mL –1 ), different times (4.5–13.5?h) of filling CCTs (cylindroconical fermentation tanks; 3?850?hL) and fermentation temperatures (8.5–11.5?°C) were modulated to?assess their impact on?the?fermentation indices. Within the?studied ranges of fermentation parameters the?experimental factors had a?significant influence (R 2 for the?model 73%) on?alcohol content, pH?(83%), extract drop?(86%), FAN?consumption?(70%), bitterness loss?(73%) and sensory analysis?(71%). Based on the?multiple response optimisation analysis, the?values of?independent factors that optimised alcohol content at the?level of 6.94%?(v/v), extract drop at?1.77?°P per day with maximization of FAN consumption (ca. 128?mg?L –1 ) and pH?drop to?the?level of?4.69?with minimized bitter substances losses (6.2?BU) were as follows: pitching rate 6?mln?cells?mL –1 ; fermentation temperature 11.2?°C; aeration level 10.5?mg?L –1 ; and CCTs?filling time 13.5?h.