Rheological properties of aqueous blends of high purity barley β-glucan with high purity commercial food gums

Rheological properties such as flow behaviour, viscosity, viscoelasticity, and thixotropy of solutions of beta-glucan purified from barley fibre concentrate and twelve commonly used food gums, alone and in combinations, were characterised using an oscillatory rheometer. Pure gums and gum combinations were evaluated at 0.5% and 0.75% (w/w) total gum concentration in aqueous medium, whereas the beta-glucan/gum ratios were kept at 90/10 or 80/20 (w/w). Viscosity synergism was observed for beta-glucan solutions in combination with xanthan, iota-carageenan. and carboxymethyl cellulose. However, barley beta-glucan blends with lambda-carageenan, Konjac, high- and low-methoxyl pectin, microcrystalline cellulose, alginate, and gum arabic showed marked lowering of the viscosity compared to beta-glucan alone. In addition, beta-glucan/xanthan gum blends demonstrated improved shear tolerance compared to xanthan dispersions alone, and soft gel transformation. Non-thixotropic behaviour was observed for 0.5 and 0.75% (w/w) beta-glucan dispersions and its gum combinations. None of the gum combinations studied demonstrated thixotropy. (C) 2009 Elsevier Ltd. All rights reserved.