Rheological Properties of Corn Starch Dispersions in Pregelatinized Starch Solution

The steady and dynamic rheology and thixotropy of corn starch dispersions in pre-gelatinized starch solution were studied using AR500 rheometer. The effects of temperature, concentration and frequency on the viscosity were investigated, respectively, and the rheological mechanism of dispersions was illustrated clearly. The rheological tests indicate that corn starch dispersions experience two stages which are shear thinning and shear thickening. Compared with the temperature, the apparent viscosity is more sensitive to the concentration at low shear rate in steady rheological measurements. It also reveals that angular frequency has more significant effects on the critical oscillatory shear stress. The greater the concentration, the higher the thixotropic energy is, and showing extreme thixotropic behavior. These are mainly due to the internal continuous network structure of dispersions destroyed at low shear rate and starch granules aggregated into particle clusters at high shear rate.