Thixotropy has been found to be a rheological phenomenon of great importance in industry including the food industry. Generally, it is a measure of substance instability owing to the formation and destruction of its internal structure. It depends on the time and rate of shear, as well as on the mechanical phenomena occurring within the material. Among other things, thixotropy is applied, on a large scale, in the confectionery industry for the purpose of describing phenomena occurring during the conching of chocolate masses. Starch gels (gruels) are characterized by a structure highly instable in time. Thixotropic characteristics are measured and applied to characterize this instability (changeability in time).