Abstract: In this paper, arabinoxylan was prepared from wheat bran by an alkali extraction method. The influences of NaOH concentration, extraction temperature and time on the monosaccharide composition, molecular mas distribution and viscosity of arabinoxylan were investigated by high-performance liquid chromatography, high performance gel filtration chromatography and rheological analysis. The results showed that with increasing alkali concentration, the purity of arabinoxylan decreased first and then increased, while the yield showed the opposite trend. As the extraction temperature and time increased, the purity and yield of arabinoxylan increased until reaching a plateau. Their values were respectively 88.72% and 32.8% under the optimized conditions: NaOH concentration 0.5 mol/L, extraction temperature 85 ℃ and extraction time 120 min. The molecular mass of arabinoxylan decreased significantly with increasing extraction temperature. The viscosity of arabinoxylan solution was positively correlated with NaOH concentration but negatively correlated with extraction temperature and time. The results of this study indicated that arabinoxylans obtained under different alkali extraction conditions were distinct in their properties. Our results in this paper can provide a theoretical basis for the alkali extraction and application of arabinoxylan from wheat bran.

Key words: wheat bran, alkali extraction of arabinoxylan, monosaccharide composition, molecular mass, viscosity