Solution Properties Of Cereal Bran Arabinoxylan

More recently, the relationship between nutritional value and physicochemical properties such as structure, molecular weight, conformation and aggregation of cereal arabinoxylans has engaged the attention of researchers. In this paper, the solution properties and conformation of alkali soluble arabinoxylan extracted from cereal bran were investigated by fluorescence spectrophotometer, dynamic laser scattering and HPSEC-MALS-RI.First, corn bran arabinoxylans were separated from corn brans and their composition was analysized by GC. The effect of concentration, temperature and solvent on the aggregation of CAX was discussed. It is found that CAX could form aggregate readily, and the aggregation of CAX become stronger with the increasing of concentration. However, with the increasing of temperature or adding of the sodium hydroxide, the aggregation of CAX become weaken. This indicates that the hydrogen bonding interaction plays the important role in the aggregation of CAX.Then,the corn bran arabinoxylan was dissolved in deionized water(4%,w/v). Fractionation was carried out by stepwise increases in ethanol concentration. Anhydrous ethanol was slowly added under continuous stirring at room temperature, when the white floc appeared, then filtered.Arabinoxylan are henceforth referred to as CF60. The structure factorρ=<R_g>/<R_h> of CF60 is 1.7 by dynamic laser scattering and HPSEC-MALS-RI,and The fractal dimension (df) of corn bran arabinoxylan chains is 1.47. From these, it is found that CF60 is a typical random coil.Finally,WF60 was separated from wheat bran. investigated The df of wheat bran arabinoxylan was 1.42 by dynamic laser scattering and HPSEC-MALS-RI,and within the limits of random coil polymer. The estimated L_p of wheat bran arabinoxylan is much higher than that of maize CF60. Considering that theρof wheat bran arabinoxylan is also higher than that of CF60, wheat bran arabinoxylan is believed to be stiffer than maize bran arabinoxylan due to the higher content arabinosyl residues hindering the rotation of the xylan backbone. The calculated C* of WF60 was lower than that of CF60, which suggests stronger intermolecular interaction within WF60 than within CF60 at the same concentration. This might be the reason why the concentration dependence of aggregation of wheat bran arabinoxylan is much stronger than that of maize bran arabinoxylan.