In the chocolate industry, it is common to use one production line for different products. To avoid contamination of one product with another, product changes involve flushing processes. In this process, a product is displaced by a subsequent product. Due to limited process knowledge of such flushing processes, it has so far been designed using rigid process parameters and large safety factors. The end of the process is determined subjectively based on the changes in color of the product discharged. This lead to unnecessary consumption of resources. To enable an improvement of flushing processes and their design in the future, three measurement methods, based on surface wave, capacitive and optical technologies, are being investigated and compared with a reference method. In addition, the influence of different flow regimes, the preliminary pipe emptying and the resulting filling condition on the flushing process are investigated. These experimental parameter studies supported by selected CFD simulations are compared and the advantages and disadvantages are presented. The most promising approach to improving flushing processes in the future appears to be the use of surface wave measurements to monitor the flushing process and the use of flushing regimes using different flow rates to reduce resource consumption.