| beta-D-Glucan extracted from wheat bran was fractionated into six fractions with a significant MW difference and a narrow MW distribution. These fractions were homogeneous and had a high value of tri/tetra ratio (4.16--4.47) compared to other cereal beta-glucans. The aggregation phenomenon in aqueous solution of beta-glucans led to incorrect conformational analysis, which was eliminated by 0.5 M NaOH solution without observed degradation of the polymer. An extended random coil conformation was confirmed by viscometry and light scattering studies. It was found that wheat beta-glucan chain was less flexible than barley and oat beta-glucan due to its higher tri/tetra ratio, which led to higher values of the characteristic ratio and statistical segment length. Increasing molecular size led to lower mobility and density of beta-glucan chains in dispersion, thus decreased gelation rate, gel strength and enthalpy of wheat beta-glucan gels. By contrast, the increase of the chain length led to an extended gel network, thus an increase in the melting point of wheat beta-glucan gels. |
