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. (c) 2006 Elsevier Ltd. All rights reserved.