Ultrasound-induced cavitation effects on microbial load, colloidal structure and techno-functional properties of Moroccan camel milk

Abstract

Camel milk is a nutritionally valuable dairy system with a distinctive mineral protein colloidal organization but remains highly perishable and sensitive to physicochemical changes during processing. This study evaluated the effects of controlled ultrasonic treatment on the microbiological stability, colloidal structure, and techno-functional properties of Moroccan camel milk. Ultrasonic processing induced strong, time-dependent microbial inactivation, achieving an approximately 2-log reduction after 5 min and complete bacterial inactivation after 15 min, without significantly altering the overall physicochemical properties. At the colloidal scale, ultrasound reduced particle size and turbidity and modified zeta potential, indicating enhanced dispersion and structural reorganization. Protein secondary structure analysis revealed a decrease in α-helix content accompanied by an increase in random coil structures, suggesting partial protein unfolding driven by cavitation-induced shear forces. Minor changes in mineral distribution, protein, and lactose contents reflected physical rearrangements rather than chemical degradation. Notably, despite these structural modifications, the emulsifying capacity remained unchanged, demonstrating preservation of techno-functional performance. These findings provide experimental evidence that ultrasonic acoustic cavitation can effectively inactivate microorganisms in camel milk while predominantly inducing sonophysical effects, thereby advancing the understanding of cavitation-driven structure-function relationships in camel milk and supporting its processing as a non-thermal, structure-preserving dairy system.