Steam pretreatment of agricultural residues facilitates hemicellulose recovery while enhancing enzyme accessibility to cellulose

Abstract

The origins of lignocellulosic biomass and the pretreatment used to enhance enzyme accessibility to the cellulosic component are known to be strongly influenced by various substrate characteristics. To assess the impact that fibre properties might have on enzymatic hydrolysis, seven agricultural residues were characterised before and after steam pretreatment using a single pretreatment condition (190°C, 5min, 3% SO2) previously shown to enhance fractionation and hydrolysis of the cellulosic component of corn stover. When the fibre length, width and coarseness, viscosity, water retention value and cellulose crystallinity were monitored, no clear correlation was observed between any single substrate characteristic and the substrate’s ease of enzymatic hydrolysis. However, the amount of hemicellulose that was solubilised during pretreatment correlated (r2=0.98) with the effectiveness of enzyme hydrolysis of each pretreated substrate. Simons’s staining, to measure the cellulose accessibility, showed good correlation (r2=0.83) with hemicellulose removal and the extent of enzymatic hydrolysis.