Rheological behavior of cooked rice flour dispersions in steady and dynamic shear

摘要

The steady and dynamic rheological properties of Korean rice flour dispersions were evaluated at different concentrations (4%, 5%, 6%, 7%, and 8%). Rice flour dispersions at 25 ℃ showed a high shear-thinning behavior (n = 0.23-0.28) with low magnitudes of Casson yield stresses (σ_(oc) = 4.1-20.1 Pa). The magnitudes of σ_(oc), consistency index (K) and apparent viscosity (η_(a.100)) increased with increase in concentration. The apparent viscosity over the temperature range of 25-70℃ obeyed the Arrhenius temperature relationship, indicating that the magnitudes of activation energies (E_a) were in the range of 0.21-0.27 KJ/mol. The power law model was found to be more suitable than the exponential model in expressing the relationship between concentration and apparent viscosity (η_a). Storage (G′) and loss (G″) moduli increased with increase in frequency (ω) while complex viscosity (η~*) decreased. Magnitudes of G′ and G″ moduli increased with increase in concentration. Cox-Merz rule was not applicable to rice flour dispersions.