Xylobiose and Xylotriose Production from Alkali Soluble Defatted Rice Bran Arabinoxylan Using Endoxylanase from Neocallimastix partriciarum

Abstract

Production of defatted rice bran arabinoxylan (DRB-AX) from defatted rice bran (DRB) is maximized using alkali extraction. Conversion of DRB-AX into xylooligosaccharide (XOS) by endoxylanase from Neocallimastix partriciarum, and refining enzymatic XOS liquor using activated carbon are also investigated. Chemical composition analysis of DRB indicates the richness of nutrients at 60.76% carbohydrate, 10.42% protein, and 32.69% total dietary fiber. Alkali extraction performed at 2.5 M NaOH solution for 12 h is the optimal condition to produce DRB-AX, with a crude yield of 52.82 g 100 g−1 containing 26.96% arabinoxylan, 26.07% arabinose, and 21.42% xylose with arabinose/xylose ratio 1.22. Endoxylanase from N. partriciarum partially hydrolyzes DRB-AX at 50 °C, pH 6.0 at enzyme concentration of 80 U g−1 substrate for 24 h. This enzymatic XOS production design yields 26.67 ± 0.69 mg g−1 DRB. Xylobiose and xylotriose including an unknown saccharide are short chain oligomer products. Refining XOS from DRB with 15% (w/v) activated carbon recover 55.7% (w/w) of initial XOS. Hence, DRB can be used as an alternative highly branched arabinoxylan source for novel substituted XOS production.