Two production lager strains were compared for their different fermentation characteristics. The response of the two strains to changes in wort dissolved oxygen level, wort original gravity, wort zinc concentration and yeast pitching rate were studied. One yeast strain was studied further where the effect of wort original gravity and wort zinc concentration on the formation of fermentation products was examined at different incubation temperatures. The production of the major beer esters, total higher alcohols and final TVD concentration was investigated for both yeast strains under the different fermentation conditions described above. The experiments were designed using Minitab, so that both the design and the interpretation of the experiments were according to statistical principles. The software was of particular use when studying the interaction of different factors, such as pitching rate and wort zinc concentration, and their influence on various responses, such as ethyl acetate production. Minitab also offers an “optimiser” tool. This was used to investigate how closely the product of one yeast strain could be matched using the other strain by varying different fermentation parameters. This work highlights the results obtained for overall fermentation residence time, final TVD concentration, ethyl acetate and iso-pentyl acetate production and total higher alcohol concentration.
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