Toward green production of xylooligosaccharides and glucose from sorghum straw biowaste by sequential acidic and enzymatic hydrolysis

Abstract

Sorghum straw, as an organic solid-waste, has a high biomass yield and is rich for xylan and glucan, making it a promising candidate for the production of value-added xylooligosaccharides and glucose. To streamline the biorefinery processes, the edible gluconic acid was used for xylooligosaccharides production and sorghum straw material pretreatment in this study. Firstly, response surface methodology was employed to maximize the yield of xylooligosaccharides, achieving a maximum xylooligosaccharide yield of 50.3% with 7.5% gluconic acid at 168 °C for 35 min; furthermore, the XOS and calcium gluconate can be co-prepared as feed additives. Meanwhile, the lignocellulosic entanglement of sorghum straw can be effectively deconstructed by acidic hydrolysis of gluconic acid and an enzymatic hydrolysis yield of 90.8% was subsequently achieved using pretreated sorghum straw solids. These findings show that gluconic acid pretreatment is able to effectively enhance the value of hemicellulose and cellulose from sorghum straw.