Cereal Chem 63:124-130   |  VIEW ARTICLE
Brewers' Condensed Solubles. III. Enzymatic Hydrolysis, Viscosity Reduction, and Fermentation.

K. M. Chung, D. S. Chung, and P. A. Seib. Copyright 1986 by the American Association of Cereal Chemists, Inc. 

Brewers' condensed solubles (BCS) were treated with glucoamylase, pullulanase, cellulase, and beta- glucanase to increase the level of yeast-fermentable sugars. Enzymatic hydrolysis with glucoamylase alone at 60 C increased the level of fermentable sugars by a factor of 1.8. Pullulanase, cellulase, and beta- glucanase did not significantly increase fermentable sugar. Glucoamylase-treated BCS (GT-BCS) was fermented at 30 C. Optimum fermentation conditions were pH 4.2, solids level 15-20% GT-BCS, and an inoculum of 0.2 g of distillers' active dry yeast/L medium. After three days of fermentation, 76-97 gal of ethanol (95%, v/v) was produced from 2,000 lb of dry BCS. Distillers' active dry yeast and bakers' compressed yeast gave comparable fermentation times and yields of ethanol on 10 and 20% GT-BCS, but brewers' spent yeast at its optimum fermentation time produced slightly more ethanol from 10% GT-BCS and slightly less ethanol from 20% GT-BCS than the other two yeasts. The viscosity of BCS at 59.1% was halved when it was treated with cellulase or beta-glucanase; cellulase was the most cost-effective enzyme.