Two-Stage Hydrothermal Processing of Wheat (Triticum aestivum) Bran for the Production of Feruloylated Arabinoxylooligosaccharides

Two-stage hydrothermal processing was employed to obtain feruloylated arabinoxylooligosaccharides (AXOS) from wheat bran. First, wheat bran in water (10% w/w solids) was heated to 130 °C, releasing 36.3% of total solids, 70.3% of starch, and 6.06% of pentose sugars. Wheat bran was then heated to 170−220 °C. Heating to 200 and 210 °C released the most AXOS (70% of the insoluble arabinoxylan) and esterified ferulate (30% of the initial ferulic acid). Treatment of 200 °C retained a higher proportion of high molecular weight (>1,338) compounds than 210 °C and was the preferred treatment temperature because autohydrolysate liquors contained lower concentrations of many contaminants. Purification of this autohydrolysate liquor with ethyl acetate extraction, vacuum concentration, and ion exchange resulted in a product containing 32.0% AXOS and 4.77% esterified ferulate, accompanied by 36.0% other oligosaccharides and free sugars, with an antioxidant activity of 29.7 μmol Trolox equivalents/g dry matter.