Green pretreatment of Xanthoceras sorbifolia Bunge husks via hydrogen peroxide presoftening, liquid hot water pretreatment and enzymatic hydrolysis for the co-production of functional xylo-oligosaccharides and glucose

Xanthoceras sorbifolia Bunge husks (XSH), a by-product of industrial production, are rich in cellulose, hemicellulose and lignin. The aim of this study was to use XSH as a new type of lignocellulosic feedstock to co-produce high yields of xylo -oligosaccharides (XOS) and glucose via an integrated biorefinery process including hydrogen peroxide presoftening, i.e., H 2 O 2 -assisted hydrothermal pretreatment (HHP), liquid hot water (LHW) treatment and enzymatic hydrolysis (EH). The HHP 1st -LHW treatment resulted in high selectivity toward hemicellulose, with a minor influence on cellulose and lignin. The maximum XOS (X 2 -X 6 ) yield of 58.5 % was achieved under optimal conditions, in which the desired functional XOS (X 2 -X 4 ) was 81.4 %, representing 10.5 g per 100 g of XSH. Moreover, HHP 2nd -assisted enzymatic hydrolysis resulted in nearly full degradation of cellulose, and a 102.9 g/L glucose titer corresponding to 95.3 % of the glucose yield was produced via the addition of 10 % glucan (≥15 % solid loading). Mass balance analysis revealed that 12.9 g of XOS, 38.3 g of glucose and 14.2 g of lignin were produced from 100 g of XSH. These results demonstrated the great potential of XSH as a renewable biomass for high value-added biochemical production. The proposed combined pretreatment method is an environmentally friendly and effective process to for co-produce high yields of desirable XOS, fermentable sugars and native-like lignin.