Rheological behaviour of steamed rice flour dispersions

Dispersions of steamed rice flour at different solid (10-50%, dry basis) concentrations have been tested for their rheological behaviour employing a rheometer with coaxial cylinder attachment. These dispersions were pseudoplastic in nature with flow behaviour index well below unity (<0.61). Yields stress, as determined by stress relaxation technique, was not noticed in 10% dispersions of solids but was found in dispersions with higher solid concentrations; it increased markedly (more than 200 times) with an elevation in rice flour solids. Experimental values of yield stresses were 1.1-18.3 times higher than those calculated using Herschel-Bulkley, Casson or Bingham plastic models. An increase in concentration of solids from 10% to 50% increased consistency index and apparent viscosity by more than 20 and 10 times, respectively, but flow behaviour index decreased by about 30%. (C) 2001 Elsevier Science Ltd. All rights reserved.