β-CD-MOF-based edible antimicrobial packaging film with humidity-controlled carvacrol release for preserving fresh strawberry.

The development of safe, environmentally friendly, edible antimicrobial packaging films represents a promising alternative to conventional plastic packaging for reducing spoilage and extending the shelf life of fresh food. Here, we propose a novel strategy to construct edible β-CD-MOF/carvacrol@zein (BCCZ) composite films by intertwining β-CD-MOF loaded with the antimicrobial essential oil carvacrol, and zein. The resulting BCCZ films exhibit high humidity-triggered, long-lasting bactericidal efficacy, effective fruit preservation, and excellent biosafety. Characterization revealed that BCCZ films possess a compact texture, hydrophilic surface, low water vapor permeability, and high humidity sensitivity. Additionally, this film act as a "storehouse" for carvacrol, enabling humidity-controlled release (96.3% release at 100% RH and only 12.0% at 43% RH on day 7). BCCZ film effectively inhibited Gram-positive Staphylococcus aureus, Gram-negative Escherichia coli, and fungi (Botrytis cinerea) through the release of liquid-phase and vapor-phase carvacrols under both direct contact and indirect contact conditions in high humidity. Owing to the film's humidity-triggered, long-term release of carvacrol, strawberries packed in BCCZ films maintained their freshness and appearance significantly better after seven days of storage at 21 °C. This work provides valuable insights and holds promise for the design and commercial application of safe, environmentally friendly freshness-preserving packaging films.