Impact of cleaning-induced surface modifications on cheese yield and quality in polypropylene molds

Cheese sticking to mold surfaces is a major issue in dairy processing, leading to product losses, quality defects, and reduced production efficiency. This study investigates how cleaning procedures and fouling affect the surface properties of polypropylene cheese molds and their role in adhesion phenomena at the mold–curd interface. Polypropylene mold surfaces exhibiting different surface energy states, representative of different degrees of use, were subjected to controlled cleaning cycles using acidic or alkaline solutions, with or without model fouling. Fouling was reproduced using a controlled matrix composed of proteins, lipids, and minerals of dairy origin, representative of a product undergoing draining, under controlled environmental conditions. Surface properties were characterized using contact angle measurements to determine surface energy and its polar and dispersive components, complemented by infrared spectroscopy and scanning electron microscopy coupled with energy-dispersive X-ray analysis.

Results show that cleaning and fouling modify surface energy, particularly its polar component, due to the accumulation of organic and mineral residues. Variations in adhesion behavior were observed depending on the number of cleaning cycles, indicating a non-linear evolution of surface properties. From an industrial perspective, these phenomena may lead to increased yield losses and demolding defects. These findings provide new insights into the mechanisms governing cheese sticking and highlight the importance of controlling surface modifications induced by cleaning in order to limit adhesion phenomena. This work contributes to improving sustainability in dairy processing by reducing product losses and optimizing cleaning strategies.