Enzymatic production of pentoses from the hemicellulose fraction of corn residues

Three commercial xylanase preparations were evaluated as a sole enzyme source for the enzymatic production of pentoses from the hemicellulose fraction of corn husks and corn cobs. The hemicellulose fraction was obtained by extracting corn husks or corn cobs with 1.25 mol/l NaOH, and the alkaline extract was used as a substrate for enzymatic hydrolysis. Rapidase Pomaliq (Gist-brocades) was found to yield significantly more pentoses from corn husks and corn conb than Clarex ML (Genenor) or Validase × (Valley Research). Rapidase Pomaliq was capable of increasing the concentration of pentoses from an initial value of 106.5 to 210.6 g/kg dry matter of corn husks or 8.6 to 141.6 g/kg dry matter of corn cobs, respectively, under favorable conditions (480 min of reaction at pH 5.0 and 50 °C). Products of the enzymatic reaction were identified as arabinose, xylose, xylobiose, and xylotriose. The results of this study indicate that Rapidase Pomaliq, an enzyme preparation derived from Aspergillus niger and Trichoderma reesei, could serve as a sole enzyme source for the production of pentoses and xylooligosaccharides from corn residues.