Intelligent Food Packaging Films Based on pH-Responsive Eugenol@ZIF-8/PVA-HACC with Enhanced Antimicrobial Activity

Natural antibacterial food packaging materials endowed with environmental responsiveness are garnering substantial research interest in sustainable food preservation. This study reports the development of a pH-responsive antimicrobial composite film through encapsulation of eugenol-a natural phenolic compound-within zeolitic imidazolate framework-8 (ZIF-8). The engineered eugenol@ZIF-8 system demonstrated pH-dependent release characteristics, with cumulative release reaching 32.2% at pH 6 versus merely 0.61% at pH 7 over 4 h. Subsequent integration of this nanocarrier into a polyvinyl alcohol (PVA)/hydroxypropyltrimethyl ammonium chloride chitosan (HACC) matrix yielded a multifunctional composite film for active food packaging applications. The characterization of film revealed that while eugenol@ZIF-8 incorporation slightly compromised mechanical strength (tensile resistance decreased by 18.7%) and flexibility (elongation at break reduced to 54.3% of control), it significantly enhanced hydrophobicity (water contact angle increased to 92.5°) and thermal stability (decomposition temperature elevated by 34 °C). The composite film demonstrated synergistic antibacterial efficacy through the combined action of Zn²⁺ ions, ZIF-8 nanostructures, and eugenol, achieving 88% inhibition against E. coli. Practical validation through fresh noodle preservation trials confirmed the material's effectiveness, with the optimized formulation (PVA-HACC-2% eugenol@ZIF-8, PHEZ2) extending shelf life by >5 days compared to conventional packaging. This work establishes a novel strategy for engineering intelligent ZIF-based packaging systems that respond to food spoilage microenvironments, offering significant potential for reducing food loss.