The thermal stability of alpha-glucosidase is important because the conversion of starch to fermentable sugars takes place at temperatures of 65-73°C. The thermolability of alpha-glucosidase results in either reduced efficiency of starch breakdown at the high temperatures used for starch gelatinization or requires that the starch be cooled to a more favorable temperature for enzymatic hydrolysis after the starch is gelatinized. To remedy this problem we created a thermostable alpha-glucosidase. In this study we tested the efficacy of the recombinant alpha-glucosidase during mashing. Mashing was conducted in the presence of non-mutated recombinant alpha-glucosidase (control) or the mutated alpha-glucosidase. The amount of glucose produced by the mashes containing the wild-type recombinant alpha-glucosidase was 9% greater than that produced by the control mashes. Experiments to determine the impact of this recombinant alpha-glucosidase upon the real degree of fermentation and the total carbohydrate profile of worts are underway.