UC Davis

The hydrolysis by β-glucanase enzymes of barley β-glucan is important in the malting process to degrade endosperm cell walls and prepare malt for later sugar extraction during mashing. Excess β-glucan from unmalted adjuncts or unevenly modified malt can have a negative effect on wort and beer quality. This thesis explores how β-glucanase activity during mashing can influence wort β-glucan, viscosity, and filtration. First, a β-glucanase method was adapted for use on a Thermo Scientific BeerMaster Gallery autoanalyzer. This method enabled the simultaneous analysis of β-glucan and β-glucanase throughout the course of two different mash profiles—a European Brewing Congress (EBC) mash starting at 45°C and a modified Institute of Brewing (IoB) mash starting at 65°C. In the lowertemperature EBC mash, malt β¬-glucanase was able to reduce wort β-glucan contributed from 10-20% additions of unmalted barley. However, the higher temperature of the IoB mash resulted in rapid enzyme denaturation, and therefore a large amount of β-glucan accumulated in the wort. Two thermostable β-glucanases were added at the beginning of the IoB mash with 10-20% barley adjunct to evaluate their impact on β¬-glucan during the course of the mash. The β-glucanase from Trichoderma quickly hydrolyzed β-glucan as it was extracted, resulting in an easily separated wort with low β-glucan. The β-glucanase allozyme from wild barley was not as thermostable as the Trichoderma β-glucanase, and thus β-glucan accumulated in the wort as β¬-glucanase activity decayed. However, the addition of wild barley enzyme was able to reduce β-glucan in 10 and 20% barley mashes by 52 and 47% respectively. This thesis finds that the IoB mash condition is susceptible to high levels of wort β-glucan when the grist includes unmalted barley. Thermostable wild barley β-glucanase is able to reduce the amount of wort β-glucan, but it is not as effective as bacterial-source enzymes that are more thermostable and already commercially available.