Comprehensive evaluation of combining hydrothermal pretreatment (autohydrolysis) with enzymatic hydrolysis for efficient release of monosaccharides and ferulic acid from corn bran

The combination of hydrothermal pretreatment (autohydrolysis) and enzymatic hydrolysis was comprehensively evaluated for the efficient release of monosaccharides and ferulic acid from corn bran. Arabinan was depolymerized and solubilized more easily during autohydrolysis compared to xylan, esterified ferulic acid, and the acetyl group. Also, the enzymatic xylose yield showed strong linear correlation with arabinan, ferulic acid, and acetic acid content in autohydrolysis residues while correlations between enzymatic glucose yield and hemicellulose contents were separated into two stages with different slopes. The addition of a few debranching enzymes to commercial cellulase and xylanase only slightly enhanced enzymatic hydrolysis of autohydrolysis residues, whereas an enzyme blend from Aspergillus oryzae and Eupenicillium parvum showed a significant synergistic effect. Desirable combined hydrolysis yields of glucose (72.26%), xylose (75.87%), arabinose (76.95%), and ferulic acid (74.13%) were obtained after autohydrolysis at 165 °C for 40 min and subsequent hydrolysis by an equal mixture blend produced by A. oryzae and E. parvum at an enzyme loading dosage of 14.1 mg protein/g dry destarched corn bran.