ZIF-8-Reinforced Biodegradable Composite Modified Atmosphere Packaging Membranes for Fruit Packaging

This study developed a novel equilibrium modified atmosphere packaging (EMAP) membrane. Zeolitic imidazolate framework-8 (ZIF-8), a highly porous material with a large specific surface area, was used as a functional filler, aiming to improve CO₂/O₂ selectivity and gas permeability, and was incorporated into a biodegradable polylactic acid (PLA) matrix for preparation. The resulting PLA/PEG@ZIF-8 membrane, containing 0.75% ZIF-8, demonstrated exceptional gas selectivity and packaging performance. Specifically, the membrane achieved a significantly enhanced CO₂/O₂ selectivity of 6.35 while maintaining favorable gas permeability. Furthermore, the water vapor transmission rate was effectively reduced. The membranes demonstrated substantial improvements in both elongation at break and tensile strength, indicating enhanced mechanical properties. In addition, the membrane retained its hydrophobicity and desirable swellability, while showing remarkedly improved UV-blocking properties. Negligible zinc ion migration was observed, ensuring safety, as confirmed by cell viability exceeding 97% in cytotoxicity assays. These characteristics contribute to maintaining an optimal internal gas composition within the package, thereby effectively inhibiting microbial growth and nutrient loss, thus extending the shelf life of cherry tomatoes. Overall, the PLA/PEG@ZIF-8 EMAP membrane demonstrates significant potential for preserving high-respiration fresh fruits, highlighting its promising application in food preservation technology. PRACTICAL APPLICATIONS: The PLA/PEG@ZIF-8 membrane was fabricated with superior CO₂/O₂ selectivity. The membrane exhibited enhanced gas permeability and packaging performance. The shelf life of cherry tomatoes was remarkably extended by packaging with the membrane.