Steady state flow behaviours of extruded blend of rice flour and soy protein concentrate

Rheological properties in terms of steady state flow behaviours of extruded dispersions (rice flour/soy protein concentrate blend), were investigated using dynamic rheometry. The effects of concentration (2%, 5%, 7%, 9% and 11%) and temperature (25–70 °C) on the rheological parameters (yield stress, flow behaviour index) of the non-expanded pellet blend (12.5% protein) were determined using common rheological models. Steady-shear viscosities in a range of shear rate from 0 to 500 s−1 were observed as a function of concentration and temperature. From typical curves showing the dependence of shear stress on shear rate, it could be observed that all suspensions exhibited a non-Newtonian and pseudoplastic behaviour. The model that best fitted the experimental data at all temperatures and concentrations was the Herschel–Bulkley model.