Effect of pretreatments on production of xylooligosaccharides and monosaccharides from corncob by a two-step hydrolysis.

Xylan extraction by alkali is usually a prerequisite for traditional xylooligosaccharide (XOS) production from corncob. In this study, to avoid xylan isolation before XOS production, corncob was delignified by hydrogen peroxide-acetic acid (HPAA), followed by a two-step enzymatic hydrolysis for XOS and monosaccharide production. High lignin removal (55.5%-82.6%) was observed upon pretreatment with 75%-100% HPAA and using 50-100 mM H2SO4 as a catalyst. A high XOS yield of 27.8% was obtained from 75% HPAA-pretreated corncob with 75 mM H2SO4, and the xylose/XOS ratio was only 0.09, indicating that the purity of XOS was relatively high. The highest glucose yield (79.1%) was obtained from 100% HPAA-pretreated corncob with 50 mM H2SO4. Finally, 58.3 g of XOS, 186.9 g of glucose, and 56.4 g of xylose were obtained from 1 kg of corncob. This study provides a promising approach for XOS and monosaccharide production from corncob without xylan isolation.