Ultrasound-induced protein-polysaccharide complexes: Mechanisms, functionalities and applications in food systems

Understanding the interaction between proteins and polysaccharides is fundamental for designing food structures, yet the potential of ultrasound to precisely modulate these interactions has not been systematically reviewed. This review critically examines the mechanistic role of acoustic cavitation and its associated physical and chemical effects in driving the formation of protein-polysaccharide complexes. We highlight how ultrasound-induced shear forces, micro-turbulence, and free radical generation not only accelerate covalent conjugation via the Maillard reaction but also reinforce non-covalent forces, such as hydrophobic interactions, hydrogen bonding, and electrostatic contacts, by inducing conformational changes in biopolymers. These ultrasound-mediated structural modifications result in significantly improved techno-functional properties, including solubility, emulsification, and foaming performance. We further discuss how these enhanced complexes are enabling innovations across emulsion stabilization, gel fabrication, bioactive compound encapsulation, and edible film formation. Finally, we identify critical research priorities, particularly the correlation between ultrasonic parameters and molecular interaction mechanisms, the structural characterization of conjugates, and the evaluation of their safety for food applications. By providing a comprehensive framework that bridges fundamental sonochemistry with food material science, this review positions ultrasound as a versatile and sustainable tool for engineering advanced food systems.