Fast and high yield recovery of arabinose from destarched wheat bran

Abstract

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°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. 4–5min of microwave heating at 150°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.