Enzymatic saccharification of hot-water pretreated corn fiber for production of monosaccharides

Corn fiber, currently produced at wet milling facilities, is readily available as a potential feedstock for production of fermentable sugars. Destarched corn fiber (DSCF) can be conveniently prepared for enzymatic saccharification by treating with liquid hot-water. Treating DSCF with hot-water (HW-DSCF) at 160 °C for 20 min dissolved 58% of the solids and 75% of the xylan. Preparations of hydrolytic enzymes were next used to saccharify the cellulose and xylan. The needed enzymes were prepared from culture supernatants of Trichoderma reesei Rut C30 and Aspergillus niger NRRL 2001, each grown on HW-DSCF. The harvested cultures were found to have a broad range of carbohydrase activities. The enzyme profiles varied considerably from one another and the preparations were determined to be most effective for saccharifying HW-DSCF when used in combination. Monosaccharide sugar yields obtained using the blended preparations were 74 and 54% of the available arabinose and xylose, respectively. Arabinose and xylose yields were both further increased to 80% by increasing the hot-water pretreatment time to 30 min and adding a commercial preparation of β-glucosidase, which also contained β-xylosidase side-activity.