Humidity‐pH Dual‐Responsive Biodegradable Films Based on Chitosan/Hydroxypropyl‐β‐Cyclodextrin for Controlled Citral Release and Cherry Tomato Preservation

ABSTRACT Postharvest spoilage of fruits and vegetables is accompanied by high humidity and acidification in the microenvironment, whereas conventional packaging materials fail to respond to these complex environmental signals. Herein, an innovative synergistic covalent‐noncovalent locking strategy was proposed to fabricate a pH‐ and humidity‐dual‐responsive biodegradable composite film. Unlike conventional single‐responsive controlled‐release systems, citral (CIT) was immobilized in the film matrix in two forms: via covalent anchoring through dynamic imine bonds and via noncovalent encapsulation by hydroxypropyl‐β‐cyclodextrin (HPβCD). This structure enables the coordinated on‐demand release of active ingredients, rather than relying on passive diffusion. The release results of the film indicated that under pH 7 and 43% RH, the cumulative release percentage of CIT was controlled below 7.88% ± 0.19%. In contrast, significant CIT release was observed in an acidic and high‐humidity environment (pH 4, 98% RH) that simulated actual fruit rotting. The pH‐triggered cleavage of imine bonds and humidity‐induced network swelling jointly endow the film with environment‐adaptive release performance, offering a new design strategy for intelligent recognition of complex biological microenvironments. Practical preservation tests demonstrated that the optimized CCPH15 film extended the shelf life of cherry tomatoes by 4–10 days. The film presented high antibacterial efficacy, with inhibition rates of 99.97% against E. coli and S. aureus . Moreover, the material attained a soil degradation rate of 42.37% ± 1.76% within 10 days. This study provides a novel theoretical basis and technical route for next‐generation smart packaging capable of precise targeted intervention in postharvest food preservation.