Rheological properties of coarse food suspensions in tube flow at high temperatures

The effects of particle concentration and carrier fluid temperature on rheological behavior of model food suspensions consisting of 1.5% CMC solution and green peas (15-30% v/v) were investigated using a tube viscometer. The flow behavior of the suspensions was represented by the power law model. The suspension consistency coefficient (m∗) increased with particle concentration and decreased with temperature, whereas the opposite trends were observed for the suspension flow behavior index (n∗). Among various theoretical, semi-empirical, and empirical equations tested for suspension apparent viscosity (μ∗) estimation, the third order expansion of Einstein equation, which was derived via the hydrodynamic approach, provided the best estimates for μ∗. Of equations tested for m∗ estimation, those in which n∗ was included offered better estimates of experimental values, with an empirical equation obtained based on the Einstein equation and the incorporation of n∗ term providing the best m∗ estimation. These findings suggest that, for concentrated coarse suspensions subjected to conditions presented here, the dependence between m∗ and n∗ is of importance and should be considered in order to achieve a better m∗ estimation. Besides, better representations for power law parameters of such suspensions may be obtained based on a theoretical expression derived for μ∗ via the hydrodynamic approach. The study presented here provides a much-needed insight toward the flow behavior of concentrated coarse food suspensions at high temperature, information of which is vital for various food processes.