초록
Destarched wheat bran (DWB) contained 47.7% hemicellulose, with an arabinose/xylose ratio (A/X) equal to 0.54. When hydrolyzed by an endoxylanase, around 25% of the DWB was solubilized within 4h mostly as monomer-free arabinoxylans (AX) and predominantly arabinoxylo-oligosaccharides (AXOS), with A/X of 0.22. After 20h, the solid residue still contained more than 35% non-cellulosic saccharides. Then, microwave heating in pressure vessels was used to extract the AX from DWB under acid to neutral pH according to a Box-Behnken experimental design. The effects of temperature, time and pH were assessed on: (1) matter solubilization, (2) its content in total and free monosaccharides, (3) HMF and 2-furaldehyde, (4) A/X of the released polymers, (5) AX remaining in the residues. Those responses were also plotted against the combined severity factors (CSF). Such processes led to fast and efficient solubilizations of the hemicellulose into AX/AXOS/monosaccharides with variable yields and proportions. Three independent runs were conducted with the parameters optimizing the total saccharides of the solubilized matter in order to verify the model. Both processes can lead to tailored AX/AXOS mixtures with various A/X, according to the intended application. The microwave-screened parameters may be upscaled in a hydrothermal reactor in a multi-product biorefinery perspective.