Effects of processing on shear rate of yoghurt

Yoghurt is an example of thixotropic material. Its behaviour can be represented in terms of the relation between shear rate and time for a given shear stress. For yoghurt that has not undergone previously processing the graph is approximately a straight line; when previous work has been done, the line is displaced. A model relating shear rate, shear stress, temperature and time is proposed. This is used to predict the displacement produced as a result of flow along a pipe. The predicted displacements are compared with experimental results.