A Combined Process for Production of Fumaric Acid and Xylooligosaccharides from Corncob

Production of fumaric acid and xylooligosaccharides from corncob was investigated using a combined process. Corncob was fractionated into a cellulose-rich fraction and a hemicellulose-rich fraction by an alkali pretreatment. The cellulose-rich fraction was converted into fumaric acid by Rhizopus oryzae in fed-batch simultaneous saccharification and fermentation (SSF). Maximal fumaric acid concentration reached 35.22 g/L at a final 15% (w/v) solid loading in the fed-batch SSF. The hemicellulose-rich fraction was converted into xylooligosaccharides (XOSs) by endo-beta-1,4-xylanase. The yield of XOSs was 62.35% after 24 h of xylanase hydrolysis. Xylobiose, xylotriose, and xylotetraose were the three major components in the XOSs. A mass balance analysis demonstrated that 100.6 g of fumaric acid and 148.1 g of XOSs were produced from 1000 g of dry corncob matter. The production of fumaric acid and XOSs by the combined process could make the utilization of corncob more efficient and more promising.