Structural and functional characterization of oxidized feruloylated arabinoxylan from wheat

Chemical and enzymatic modifications of carbohydrates offer a promising way of producing new fibre rich food ingredients since these methods modify the functionality of carbohydrates. Hydroxyl radical oxidized and oxidatively crosslinked (peroxidase/hydrogen peroxide) feruloylated arabinoxylan (AX) isolates were prepared and examined for structural and functional properties. It was demonstrated that hydroxyl radical oxidation provokes polymer degradation: considerable decrease in molecular size was observed with size-exclusion HPLC. Neither a change in the arabinose/xylose ratio nor in the ferulic acid content could be observed upon hydroxyl radical oxidation. Crosslinked AX had reduced monomeric ferulic acid content in comparison with the other samples indicating oxidative ferulic acid dimerization. The bile acid-binding capacity of crosslinked AX was significantly higher than that of the non-treated, or hydroxyl radical-oxidized samples suggesting that the gel structure enhanced the bile acid retention capacity of the polymer. This result suggests that crosslinked AX may have enhanced cholesterol lowering effect compared with native AX. Furthermore, it was demonstrated that hydroxyl radical oxidation of AX lowered the water absorption of white flour blended with AX, and reduced the viscosity measured with Rapid Visco Analyser while crosslinked AX increased these values. The modified functionality might open up new prospects of the application of oxidized AX in functional food. (C) 2016 Elsevier Ltd. All rights reserved.