Xylitol fermentation using hemicellulose hydrolysate prepared by acid pre‐impregnated steam explosion of corncob

Abstract

AbstractBACKGROUNDSteam explosion is widely used on a variety of plant biomass for the hydrolysis of hemicellulose. However, hydrolysis by steam explosion suffers from low xylose yield, long hydrolysis time and high energy consumption, which impede the xylitol fermentation step. This study used a dilute sulfuric acid pre‐impregnation prior to the steam explosion to prepare corncob hemicellulose hydrolysate which offers high xylose yield for xylitol fermentation by Candida tropicalis.RESULTSAfter pre‐impregnation with 0.3% (wt) dilute sulfuric acid at a liquid to corncob ratio of 3 for 6 h, corncobs were steamed at 200 °C for 5 min to obtain a maximum xylose yield of 23.5% in the hydrolysate. The hydrolysate was detoxified by concentrating with vacuum evaporation followed by adsorption using activated carbon. The detoxified hydrolysate was then used for xylitol fermentation. Maximum xylitol yield of 75.1%, volumetric productivity of 2.01 g L‐1 h and biomass of 20.9 g L‐1 were obtained from the detoxified hydrolysate.CONCLUSIONFindings suggested that this acid pre‐impregnated steam explosion strategy provides a highly effective way to prepare hemicellulose hydrolysate with high xylose yield, and could be potentially applied to industrial xylitol fermentation. © 2013 Society of Chemical Industry