Separation of water-soluble substances from steam exploded slurry for valorization of xylooligosaccharides and glucose

Co-valorization of cellulose-derived sugar and process byproducts has implications for both financial and environmental burdens associated with a biochemical conversion process. This study examined the impact of variations in the pretreatment severity on the final yield of cellulose-derived sugar as well as hemicellulose-derived byproducts, such as xylose and xylooligosaccharides, through separate enzymatic hydrolysis (SEH) of pretreated slurry (PS). Washed pretreated solid (WPS) showed about 20% higher cellulose to glucose conversion rate than PS, while xylose recovery yield decreased about 90%. In supernatant of pretreated slurry (SPS), xylose and xylooligosaccharides were present together, although concentration of xylooligosaccharide decreased with higher pretreatment severity. Enzymatic conversion rate of xylooligosaccharides in SPS to xylose decreased from 73% to 41% as pretreatment time increased from 5 to 25 min at 190 ℃. This analysis showed that the higher pretreatment severity decreased the enzymatic conversion rate of xylooligosaccharide in SPS of miscanthus. Substrate suitability for enzymatic hydrolysis could be affected by side-chain consisted of other sugar or water-soluble lignin attached to shorter xylooligosaccharide backbone.