Role of hemicellulose removal during dilute acid pretreatment on the cellulose accessibility and enzymatic hydrolysis of compositionally diverse sugarcane hybrids

Three diverse sugarcane hybrids were pretreated with dilute sulfuric acid to evaluate the role of hemicellulose removal on the efficiency of enzymatic conversion of glucan. The main pretreatment effect along with increasing reaction intervals was the selective removal of hemicellulose, which enhanced the efficiency of glucan enzymatic hydrolysis up to 63% conversion. The hybrid with the lowest initial lignin content showed the highest enzymatic conversion efficiency. Cell wall porosity of pretreated materials decreased after hemicellulose removal, which suggests lignin redistribution into the cell walls. Post-delignification of acid-pretreated samples enhanced enzymatic glucan conversions to 92-100%. The accessible surface of glucan was estimated based on Simons' differential stain technique, which correlated with enzymatic glucan conversion efficiencies and with an intrinsic sample parameter of pretreated samples that we named available glucan. Available glucan was defined as the ratio of glucan content to the sum of non-glucan components of the samples. Enzymatic glucan conversion levels fit properly with available glucan values.