Coproduction xylo-oligosaccharides with low degree of polymerization and glucose from sugarcane bagasse by non-isothermal subcritical carbon dioxide assisted seawater autohydrolysis

Abstract

High pretreatment temperature is necessary to obtain xylo-oligosaccharides (XOS) with low degree of polymerization (DP). However, traditional isothermal pretreatment for XOS production may increase the generation of xylose and furfural with the reaction time extending (10–100 min). In this study, non-isothermal subcritical CO2-assisted seawater autohydrolysis (NSCSA) firstly used seawater and CO2 for the coproduction of XOS with low DP and glucose. 51.44% XOS was obtained at 205 °C/5 MPa, and low-DP (2–4) XOS accounted for 79.13% of the total XOS. Furthermore, the specific surface area and total pore volume of the pretreated sugarcane bagasse (SCB) were 1.96 m2/g and 0.011 cm3/g, respectively, increased by 148% and 83% than that of nature SCB. Compared with subcritical CO2 pretreatment, NSCSA is an efficient method for the coproduction of XOS with low DP and glucose through inorganic salts in seawater and H2CO3 formed from CO2.