Study of the relationship between structure and functional properties of wheat beta-D-glucans

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Li, Wei
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University of Guelph

[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.

[beta]-D-Glucan, wheat bran, wheat beta-D-glucans, structure, functional properties