Maltose and glucose utilization during fermentation of barley and sorghum lager beers as affected by β-amylase or amyloglucosidase addition

Abstract

The effect of supplementation of amyloglucosidase or β-amylase during mashing of sorghum and barley beers was studied. The research focused in the increments in maltose and glucose concentrations, and their consumption during 144 h fermentation of lager beers. Barley, red sorghum and white sorghum malt beers, produced with regular or waxy sorghum adjuncts, and supplemented with these exogenous enzymes, were produced. The addition of exogenous enzymes increased up to 20% the total sugar content. Regression lines to describe sugar consumption were obtained (R2 > 0.951). Amyloglucosidase treatments had higher glucose contents and up to 4 times higher glucose consumption rates compared with unsupplemented or with β-amylase treatments. The latter treatments had maltose as predominant sugar. Amyloglucosidase treatments had higher ethanol production rates, however the maximum production rate was delayed 24 h, compared with maltose-rich treatments. These worts observed incomplete fermentations and contained higher residual sugars. β-amylase treatments were not significantly different compared with their regular counterparts in terms of sugar and ethanol production. The selection of adequate sorghum cultivars for malt and adjuncts as well as the use of an osmotolerant yeast should be considered when exogenous enzymes are supplemented in brewing.