Biodegradable bioactive packing films based on zein and β-CD-MOFs for grapes preservation

The growing concern over food safety and environmental pollution has stimulated the development of multifunctional biodegradable films. Herein, β-Cyclodextrin metal-organic frameworks (β-CD-MOFs) were prepared as loading carriers for chlorogenic acid (CGA) and silver nanoparticles (Ag NPs). These materials (CGA-Ag@CD-MOFs) were then added into a zein matrix to construct bioactive packaging films (MOFs-Zein). SEM showed that appropriate content of CGA-Ag@CD-MOFs (2 wt%) promoted the formation of a more uniform and denser film structure. FT-IR verified that hydrogen bonding between CGA-Ag@CD-MOFs and zein matrix endowed MOFs-Zein-2 % with superior tensile strength (24.61 ± 2.58 MPa), elongation at break (5.01 ± 0.71 %), barrier properties of water vapor (1.84 × 10^-7 g·m^-1·h^-1·Pa^-1) and oxygen (0.63 × 10^-10 g·cm/cm²·s). Moreover, it can control the release of both CGA and Ag⁺, which displayed high-efficiency antioxidant and antimicrobial activities against Escherichia coli O157:H7 and Staphylococcus aureus. Comprehensive biosafety evaluation through cytotoxicity (Caco-2 viability >98 %), hemolysis (< 5 %), and acute toxicity studies confirmed material safety. When applied for grape storage, MOFs-Zein-2 % effectively preserved nutritional quality and texture, and prolonged the shelf-life of grapes by 16 days. Importantly, complete biodegradation occurred within 40 days. This study provides a simple strategy for constructing of high performance of biodegradable packing films.