Impact of CO_2-Induced Anaerobiosis on the Assessment of Brewing Yeast Flocculation

摘要

For the production brewer, predicting fermentation performance may also involve the determination of the flocculation capacity of a given yeast slurry. Several methods have been reported, and a few, most notably the Helm's test, have been adopted as recommended methods of analysis by the industry. It has been suggested that the Helm's test could be further adapted to include additional extrinsic factors known to influence flocculation. In the current study, the impact of CO_2-induced anaerobiosis on this key fermentation performance indicator was investigated. The flocculation of aerobically and CO_2-induced anaerobically incubated NewFLO lager brewing yeast strains was quantified using a modified version of the Helm's test. It was observed that the rate of onset and extent of expression of flocculation were modified in response to CO_2-induced anaerobic incubation in all the yeast strains assessed in the study. It is suggested that the quantification of flocculation during CO_2-induced anaerobic incubation rather than the currently utilized aerobic incubation provides a more representative and predictive assessment of the performance of this attribute during a production-scale brewery fermentation.