Improving Sugar Extraction from Brewers’ Spent Grain Using Sequential Deproteinization and Acid-Catalyzed Steam Explosion in a Biorefinery Context

Abstract

Brewers’ spent grain (BSG) is a complex biomass composed of sugars and lignin, with a high protein content. In this work, a BSG fractionation process was evaluated to improve sugar extraction. The developed process involved a sequential combination of enzymatic deproteinization and acid-catalyzed steam explosion (SE) pretreatment. Temperature and time effects on the SE pretreatment of deproteinized BSG (BSG-D) were experimentally studied. The deproteinization yield of BSG was 63.9% and, in the liquid after SE, up to 49.8% of xylose was recovered using BSG-D. The maximum conditions of the SE were evaluated at 173.5 °C for 15.5 min with acid-catalyzed H2SO4 (0.5% w/v) in the study region. Under these best scenario, 30% and 93% of xylose and arabinose, respectively, were recovered as monomeric sugars in the liquid; from the solid, up to 72.2% glucose was recovered using enzymatic hydrolysis (EH).