Factors Influencing Maltotriose Utilization During Brewery Wort Fermentations

The uptake of maltotriose by lager and ale brewing yeast strains during wort fermentation under various environmental conditions has been investigated. Lager yeast strains utilized maltotriose faster than did ale yeast strains in all of the fermentation conditions studied. Enhanced maltotriose assimilation was obtained by agitating the lager yeast culture, supplying oxygen to the wort, increasing the fermentation temperature, and increasing the pitching rate. On the other hand, low pH, high initial wort osmotic pressure, and high ethanol levels reduced maltotriose uptake. The addition of assimilable nitrogen and major cations to wort had no detectable effect on maltotriose uptake. Increasing the pitching rate relieved some of the detrimental effects of osmotic pressure, ethanol, and low pH. The inoculum growth phase was not a determining factor on maltotriose utilization. In addition, inocula could be stored for up to 24 days at 4°C and reused five times with no effect on maltotriose utilization.