Nanoconfinement-assisted interfacial engineering for reliable intelligent κ-carrageenan/Zein films

Reliable intelligent food packaging films based on polysaccharide–protein composites are often limited by interfacial incompatibility and unstable colorimetric responses under complex environments. Herein, a nanoconfinement-assisted interfacial engineering strategy is proposed to construct reliable intelligent κ-carrageenan/Zein films by incorporating anthocyanin-loaded zeolitic imidazolate framework-8 (Cy@ZIF-8) as an active interfacial nanomodulator. In this composite system (Cy@ZIF-8/Kc/Zein), Cy@ZIF-8 simultaneously stabilizes anthocyanins through confinement effects. It also reorganizes the polysaccharide–protein network via hydrogen bonding, electrostatic interactions, and coordination interactions, effectively suppressing phase separation and promoting the formation of a homogeneous polymer matrix with a uniform thickness of approximately 0.052 mm. As a result, the Cy@ZIF-8/Kc/Zein film exhibited altered water and gas transport behaviors, showing a high swelling ratio of 4154%, a low moisture absorption of 8.19%, and a reduced water vapor transmission rate of 0.549 × 10 −8  kg·m·m −2 ·s −1 ·Pa −1 . These structural features further led to enhanced functional performances, including antioxidant activity with DPPH and ABTS scavenging efficiencies exceeding 80% at 7.5 mg/mL. Additionally, the film showed synergistic antibacterial properties against Escherichia coli and Staphylococcus aureus with survival rates decreasing to 15.29 ± 0.50% and 1.42 ± 0.31%, respectively. Application validation assays confirmed reliable chromatic evolution of the composite film under complex environmental conditions. Therefore, this study demonstrates that MOF-based nanostructures can function as effective interfacial regulators to tailor structure–property relationships and improve functional reliability in polysaccharide–protein intelligent packaging films.