Stimulus-responsive nano-enabled chitosan-based films and coatings incorporating essential oils for active food...

Stimulus-responsive chitosan-based films and coatings incorporating essential oils (EOs) are emerging as promising active food packaging systems capable of delivering antimicrobial and antioxidant functions on demand. Compared with conventional chitosan or free-EO formulations, these nano-enabled materials offer improved EO stabilization, reduced premature volatilization, and more controlled release behavior in response to environmental triggers such as pH, moisture, temperature, and, in some cases, ionic strength or other spoilage-associated changes. This review examines how nanoencapsulation strategies, including nanoemulsions, polymeric nanoparticles, nanoliposomes, and electrospun nanofibers, modify chitosan matrix structure and release kinetics. It also discusses how these interfacial and structural changes enable stimulus-responsive performance. Particular attention is given to the mechanistic basis of triggered release, including matrix swelling, polymer relaxation, diffusion control, and the disruption of hydrogen-bonding and crosslinking networks under changing storage conditions. The review further evaluates the practical effectiveness of these systems in fresh produce, muscle foods, and minimally processed products. It highlights both their shelf-life extension potential and the limitations imposed by real food matrix interactions, sensory constraints, and scale-up challenges. Finally, safety, migration, regulatory, and industrial translation issues are discussed to clarify the current readiness of these smart packaging systems for commercial application. This review highlights stimulus-responsive release as a key design principle for future chitosan-EO active packaging and identifies key research priorities for advancing these systems toward practical food preservation use.