Modelling the time-dependent rheological behavior of semisolid foodstuffs

Many of food products exhibited the thixotropic behavior, in which, the apparent viscosity of material decreases with time of shearing at constant shear rate. The structural kinetic model (SKM) was used to characterize the thixotropic behavior of three different kinds of food products. Foods selected for analysis represent the fluid and semisolid food materials. They include milled sesame, concentrated yogurt and mayonnaise. The SKM postulates that the change in the rheological behavior is associated with shear-induced breakdown of the internal structure of the food product. This model for the structure decay with time at constant shear rate assumes nth order kinetics for the decay of the material structure with a rate constant, k. The dependence of the degree and the extent of thixotropy of the materials on the temperature, composition and shear history of the food product was determined.