Enzymatic hydrolysis of steam-exploded sugarcane bagasse using high total solids and low enzyme loadings

Hydrolysis of phosphoric acid-impregnated steam-treated sugarcane bagasse was pre-optimized using a face-centered central composite design in which the process variables were the substrate total solids (TS, %), agitation intensity (AI, rpm) and enzyme loading (EL, g g(-1)). Pretreatment was carried out at 180 degrees C for 10 min using cane bagasse with 50 wt% moisture content containing 9.5 mg of H3PO4 per gram of dry biomass. Hydrolyses were performed for 96 h at 50 degrees C using Cellic CTec2(R) and water-washed steam-treated substrates. The highest amount of fermentable sugars was obtained with 20 wt% TS, producing 76.8 g L-1 of glucose equivalents, which corresponded to a total glucan conversion of 69.2 wt% and to a theoretical net increase of 39% in ethanol production from the same sugarcane tonnage without considering the use of leaves, tops and the additional yields from C5 sugars. (C) 2014 Elsevier Ltd. All rights reserved.