Ultrasound-assisted edible emulsion coatings for postharvest preservation: Cavitation-guided interfacial remodeling, droplet-to-coating translation, and scalable sonoprocessing

Ultrasound-assisted emulsification is increasingly used to formulate food-grade emulsions and active edible coatings, yet preservation performance is still frequently inferred from droplet size, polydispersity, ζ-potential, and bulk stability. These descriptors do not establish whether an emulsion retains its designed function after spreading, drying, adhesion, and storage on a heterogeneous, metabolically active food surface. This review develops a cavitation-guided framework that connects delivered acoustic energy and reactor-dependent bubble dynamics with emulsifier remodeling, interfacial assembly, emulsion architecture, droplet-to-coating translation, and postharvest function. Direct experimental evidence is distinguished from mechanistic interpretation and testable design hypotheses. Quantitative comparisons of ultrasound, high-pressure homogenization, rotor–stator processing, and hybrid approaches are used to define formulation-specific processing windows rather than a universal optimum. Nanoemulsions, Pickering emulsions, multilayer emulsions, multiple emulsions, and emulgels are assessed according to surface coverage, interfacial robustness, barrier-release coupling, compartmentalization, and residence. Particular emphasis is placed on wetting, drying, droplet immobilization, adhesion, water and gas transport, active-compound flux, and coating failure. Finally, evidence gates are used to distinguish formulation readiness, coating readiness, produce validation, and industry readiness, with throughput, energy use, thermal control, hygienic operation, migration, sensory acceptance, and process reproducibility treated as non-substitutable constraints. This framework shifts ultrasound-assisted coating design from empirical droplet miniaturization toward quantitatively defined, reactor-aware, and commodity-specific sonoprocessing.