Rheology of highly viscous masses

A tiresome issue that concerns many chocolate manufacturers is thickening of milk chocolates, which often occurs unexpectedly during production or storage. One known cause of this behavior is the fluctuating, non-robust raw material quality of milk powders from different manufacturers. The effects of any occurring thickening usually manifest themselves in disruptions to production processes or, in extreme cases, as food waste. As part of their lean activities to eliminate waste, companies rely on reliable prediction of viscosity of milk chocolates and its change over time. The closed cavity rheometer (CCR), which is to be investigated in terms of its suitability within the scope of this research work, has great potential to make reliable predictions for the behavior of chocolate masses as a function of the formulation and raw materials used. This would allow companies to minimize disruptions in production processes and thus increase their competitiveness. So far, predictions about the suitability of milk powders and the necessary insights into the thickening process itself have been lacking. Thickened masses cannot be measured in conventional rheometers because they are not flowable enough or too heterogeneous to be examined. By means of the novel CCR, such plastic masses can be measured. In our project, the CCR will be tested and used for quality assurance for the first time. So far, such CCR devices have only been applied to protein concentrates and have not yet been used in chocolate technology. Thus, for the first time, it is possible to investigate different milk powders in corresponding milk-containing masses. Until now, it has not been possible to clarify whether the cause of the problem lay in the properties of the milk powder or in unsuitable parameters of the formulation, processing and liquid storage. This is where our project starts and will contribute to solutions for the explained problem.