Rheology of starch–milk–sugar systems: effect of heating temperature

This study aims to investigate the effect of heating temperature on the rheological behavior of starch–milk–sugar (SMS) pastes. Different concentrations of corn and wheat starch were heated in liquid skim milk containing 8 wt% sugar at 60, 75, 85 and 95 °C. The sugars used are glucose, sucrose and fructose. The pastes heated at 60 and 75 °C show the same low value of viscosity. As the heating temperature increased to 95 °C, a great increase in the apparent viscosity of the paste was observed. This means that the degree of gelatinization of starch heated at 60 and 75 °C was insignificant. On the other hand, the pastes exhibited a time-independent behavior at low heating temperature (60 and 75 °C) and changed to a thixotropic behavior with increasing the heating temperature. One exception was the 2 wt% wheat–milk–glucose paste, which shows an antithixotropic behavior. The Herschel–Bulkley model was used to fit the flow curves of SMS pastes. The yield stress and the consistency coefficient increased with increasing the heating temperature and starch concentration, reflecting the increase in paste viscosity.