Fast and high yield recovery of arabinose from destarched wheat bran

Enzymatically destarched wheat bran (DWB) contained 13.8% of arabinose and 23.1% xylose. Up to a maximum of 70% of the arabinose was progressively released from DWB when heated at 80 or 100 degrees C in media acidified with HCl. Whereas microwave irradiation at higher temperatures in pressure vessels could lead to higher yields of extraction. A Box-Behnken experimental design established an efficient model describing the effects of temperature, irradiation duration and pH on arabinose extraction. The pH appeared as the most important factor of the process. 4-5 min of microwave heating at 150 degrees C and pH 1 appeared as a fast and highly efficient method to recover more than 90% of the arabinose of DWB. The percentages of arabinose were also plotted against the combined severity factors calculated from the integration of the temperature/duration/pH conditions applied. Under microwave heating, high free xylose release could also occur. The experimental design led to a quadratic model predicting the release of xylose from DWB. A range of conditions enabled to minimize xylose and hydrolyze around 50% of the total arabinose, yielding a high purity fraction. An alternative would be to release more than 90% of both arabinose and xylose, for further arabinose purification or for a common valorization of both pentoses. (C) 2012 Elsevier B.V. All rights reserved.