Production of xylooligosaccharides from corncobs using ultrasound-assisted enzymatic hydrolysis

Xylooligosaccharides were obtained using ultrasound-assisted enzymatic hydrolysis from xylan that was alkali extracted from corncobs. Effects of alkali treatments on xylan extraction were investigated. The influence of operational conditions in ultrasound-assisted enzymatic hydrolysis on xylooligosaccharide production was also studied. Optimal conditions for xylan extraction were determined to be an alkaline concentration of 15%, a corncobs to alkaline solution ratio of 1:20, a reaction temperature of 100°C, and a reaction time of 2 h. Optimal conditions for xylanase-catalyzed hydrolysis of xylan to xylooligosaccharides were determined to be an enzyme concentration of 4 g/L, an ultrasound power of 200 W, a reaction temperature of 50°C and a reaction time of 10 min. Using a combination of ultrasound and enzyme increased the reducing sugar content by approximately 50%, compared with using of enzymes alone. Ultrasound and enzymes exert a synergistic effect.