Dilute and semi-dilute solution properties of (1→3), (1→4)-β-D-glucan, the endospenn cell wall polysaccharide of oats (Avena sativa L.)

This paper describes the solution rheology of a high MW beta-D-glucan, [eta] = 9.3 +/- 0.5 dl/g, extracted and purified from oat bran. The semi-dilute solution behaviour, when characterised by steady and dynamic shear rheometry, was found to exhibit properties consistent with those of an entangled polysaccharide system. The steady shear data for the concentration (C) region from 0.2 to 2% (w/w) oat beta-D-glucan solutions were fitted to the Cross equation over a wider range, in terms of the C[eta], than investigated previously. For the higher concentration samples, >similar to 2.7%, there was less indication of a zero-shear rate Newtonian plateau. Data for the calculated zero-shear rate viscosity for the latter systems did not fall on the well-known master curve. Instead they showed a systematic deviation, and followed a yield stress modified Cross equation of Rayment and co-workers indicating behaviour more consistent with that of a filled or disperse system, than of an entangled polymer solution. (C) 2003 Elsevier Ltd. All rights reserved.