Fabrication and postharvest application of alginate/pullulan composite films integrated with citral-loaded α-CD-MOFs for sustainable cherry storage

Cherries are highly susceptible to spoilage after harvest due to physiological and biochemical changes. This poses considerable challenges to food safety. Common fungal pathogens responsible for decay include Aspergillus niger and Cladosporium cladosporioides. Citral, an efficient antifungal agent, is thought to combat these pathogens through interactions with phytase (phyA) and N-myristoyltransferase (NMT), a hypothesis explored through molecular docking simulations. Using the Independent Gradient Model based on Hirshfeld partition (IGMH) analysis, it was found that citral encapsulated within α-cyclodextrin metal-organic frameworks (α-CD-MOFs) forms strong van der Waals forces and exhibits hydrogen bonding. These interactions enhance the stability of the composite material. Incorporating citral-loaded α-CD-MOFs into a matrix of sodium alginate and pullulan resulted in a novel composite film. This film exhibits significantly improved flexibility and tensile properties, which is beneficial for fruit packaging. Meanwhile, the Higuchi and Ritger-Peppas models both indicate that citral is released by diffusion from a uniform polymeric matrix. When applied to cherry preservation, the film exhibited significantly better cherry preservation at 4 °C than at 30 °C (P < 0.05). Simultaneously, the combination of low temperature with the film's barrier properties and sustained antimicrobial release synergistically inhibited microbial growth and fruit metabolism, effectively delaying spoilage and supporting its application in both cold-chain and ambient-temperature transport.