An integrated biorefinery process for adding values to corncob in co-production of xylooligosaccharides and glucose starting from pretreatment with gluconic acid.

Increasing attention has been paid to the production of high value-added products from lignocellulosic biomass. This study aims to valorize corncob, utilizing it as feedstock for a multi-biorefinery framework, using gluconic acid in the pretreatment. In attempts to maximize yield of xylooligosaccharides, corncob was first subjected to hydrolysis by gluconic acid using response surface methodology, from which the maximum xylooligosaccharides yield of 56.2% was achieved using 0.6 mol/L gluconic acid at 154 °C for 47 min. Results indicated that gluconic acid was an effective solvent for xylooligosaccharides production: a total of 180 g of xylooligosaccharides was obtained from 1 kg corncob as a result of hydrolysis. Moreover, 86.3% conversion of cellulose was achieved from enzymatic hydrolysis of gluconic acid-treated corncob at 10% solids loading. This study presents a strategy for valorizing corncob using it to produce xylooligosaccharides and glucose, which should pave the way for valorizing other agriculture wastes.