The rolling-disc milling texture-sorting of raw straw facilitates the reduction of steam explosion intensity

Abstract

Lignocellulosic fermentable sugars have been attracting increasing attention due to the developments of synthetic biology, yet the heterogeneity of the raw material results in high pretreatment intensities and the generation of numerous fermentation inhibitors. In this study, the rolling-disc milling texture-sorting was established for raw material to mitigate inhibitors generation at its source, specifically targeting the variances in mechanical strength among corn straw tissues. Through the texture-sorting of raw corn straw, the low modulus of elasticity tissues in corn straw were crushed into soft-texture sorts and the high-strength tissues were retained as hard-texture sorts. The results showed that the steam explosion pretreatment intensity required for soft-texture sorts decreased by 77.34 %, from 1125.96 (180 °C, 5 min) to 255.10 (160 °C, 5 min), compared to the hard-texture sorts. The concentrations of inhibitors in the enzymatic hydrolysate of soft-texture sorts decreased by 55.10 %, from 8.13 g/L/(100 g/L total sugars) to 3.65 g/L/(100 g/L total sugars), indicating an improved suitability for enzymatic hydrolysate preparation. Therefore, the rolling-disc milling texture-sorting method was proposed to provide a new approach for the preparation of lignocellulosic fermentable sugars.