Modification Of Bran Arabinoxylan And Its Application

In this paper, the alkali soluble non-starch polysaccharide (AS-NSP) was extracted from corn and wheat bran by alkali-hydrogen peroxide method. The simple sugar components of AS-NSP extracted from corn bran were analyzed by gas chromatography. The results demonstrated it contained 89.13% arabinoxylan, in which arabinose and xylose ratio (A/X) was about 0.667. The molecular weight of AX extracted from corn bran (CAX) was 5.72×105g/mol measured by gel permeation chromatography method and 2.25×106g/mol measured by static laser light scattering method.Further, the CAX was chosen to modify, i.e. the CAX was etherified by 1-bromobutane, 1-bromododecane and 1-bromohexadecane, separately, to be more hydrophobic. The structure of product was characterized by infrared spectrum and 1H-NMR spectrum. The molecular weight of modified CAX under different reaction conditions was determined by static laser light scattering. The results indicated that the product (C12-AX) with more alkyl chains and less degradation of main chain was obtained in the condition of reactant mole-ratio 1:1, reaction-temperature 50℃, reaction-time 3h and had higher molecular weight. The solubility of CAX and C12-AX demonstrated that modification made CAX more hydrophobic and the product (Cn-AX) with longer carbon chain had stronger hydrophobicity.The solution behavior of CAX and modified CAX was investigated by drop shape measurement, fluorescent molecular probe, laser light scattering and rheometer. The solution behavior of modified CAX changed significantly compared with that of CAX. Long hydrophobic carbon chains trended to arrange in solution surface orderly and thus reduced water surface tension to 63.48mN/m. C12-AX could aggregate as spherical in water solution through hydrophobic interaction and the critical associating concentration (CAC) was about 0.08mg/ml. The viscosity of C12-AX water solution increased significantly when its concentration reached 3.0%(w/w). Modified CAX with more hydrophobic aggregation areas in higher concentration solution would form network, which resulted in higher viscosity. The product (C16-AX) with longer carbon chain was gelatinous when its concentration reached 6.0%(w/w). The results of rheometer indicated that the water solution of product (C12-AX) with more alkyl chains and less degradation of main chain, which was obtained in the condition of reactant mole-ratio 1:1, reaction-temperature 50℃, reaction-time 3h, had higher viscosity.The emulsion properties were investigated by observation and particle size calculation by optical microscope photograph. The results demonstrated AX absorbed on the interface of O/W drops to make emulsions stability. Modified CAX could aggregate in water solution through hydrophobic interaction between long carbon chains. The hydrophobic aggregation areas would surround oil drops to prevent drops collision and water closing to oil drops. Consequently, the product (Cn-AX) with longer carbon chain which would form bigger hydrophobic areas had stronger emulsify capability and could make emulsion more stable.