A new on-line process rheometer for highly viscous food and animal feed materials

Rheological characterization of food and animal feed materials during manufacture is necessary to optimize processes, also to achieve better quality of products. Existing laboratory instruments measure accurately rheological parameters, but the complex rheological behavior of food/feed materials depends upon time, shear, temperature, pressure and process history that restricts the validity of results when retrieving information to the process. A new rheometer is developed having a similar working principle to the ones used during manufacturing process. The system allows measurement of materials taken form the process in a continuous manner. The developed rheometer uses torque and rotational speed to predict viscosity by means of an average shear stress and a mean shear rate. From a first prototype, it was possible to predict viscosity with an accuracy of ±25 Pa s over a large range of viscosities (30–450 Pa s), using polybuthene-1 as the process fluid. More research and developments are needed to describe additional capabilities given by an exchangeable die that can extend the range of viscosity measurements.