Rheological characterisation of starch based food products under unsteady temperature conditions and high heating rate

In order to simulate a thermal process, rheological measurements under unsteady temperature conditions at high heating and cooling rate were performed. A simple thermal model was established in a Couette geometry (concentric cylinders). This model takes into account the temperature gradient in the gap which is a function of heating rate and the time response of the system. Temperature gradient was used to explain observed rheological behaviour. The model was validated using Newtonians fluids (glycerol and sucrose solution (60% w/w )) as well as Non Newtonians fluids (gelatinised starch), where their thermal dependency is well known. The approach developed in this work was used to follow the rheological changes generated by starch gelatinisation during heat treatment.