Cavitation in High-Pressure Homogenizers - Investigation of an Experimental Method Based on Free Radical Formation

Sammanfattning

High-pressure homogenizers (HPHs) are widely used in the food industry for breaking down droplets and particles to improve product stability and mouthfeel. HPHs are prone to cavitation, characterized by the formation and collapse of vapor bubbles, leading to wear and reduction in efficiency. This study evaluates the potassium iodide (KI) oxidation method as a tool for measuring cavitation. The method is based on the principle that oxidation of KI to triiodide ions only occurs in the homogenizer if the solution is subjected to cavitation. The project aims to critically evaluate the effectiveness of the KI method and use it to investigate the correlation between cavitation and homogenizing pressure. The aim is also to investigate the potential suppression of cavitation by the application of back pressure. In addition, the KI method is validated using ultrasonication due to its controlled cavitation conditions. The results indicate that the KI method is effective for ultrasonication, as there is a linear increase in triiodide formation with sonication time, suggesting cavitation. However, the results also suggest that the method may not be as effective to detect cavitation in hydrodynamic environments as in acoustic environments. No correlation between homogenizing pressure and triiodide formation was observed for HPHs, contrary to theoretical models and previous studies. In addition, the effect of back pressure gave inconclusive results, possibly because of low triiodide formation. While the KI method shows potential for ultrasonication, the results suggest that it is unsuitable for HPH. Future research should focus on alternative experimental methods to measure cavitation in HPHs.