Mussel-inspired chitosan-tannic acid-Fe3+ coatings with enhanced interfacial adhesion and multifunctional preservation for fresh fruits.

A mussel-inspired chitosan-based coating with enhanced interfacial adhesion was developed via metal-phenolic network formation by incorporating tannic acid (TA) and Fe3+ into chitosan (CS). The CS/TA/Fe coating exhibited significantly improved wettability and adhesion on fruit surfaces, as confirmed by contact angle measurements, adhesion work calculations, and molecular dynamics simulations showing stronger binding affinity to the fruit wax model (C31H64). The coating demonstrated potent antibacterial activity against Escherichia. coli (93.07%) and Staphylococcus. aureus (83.77%), strong antioxidant capacity (ABTS 96.72%, DPPH 89.66%), and effective antifungal activity against Colletotrichum spp. On passion fruit, CS/TA/Fe coating delayed senescence by reducing weight loss, maintaining firmness, suppressing decay, and modulating the epiphytic microbial community. On mango, it significantly inhibited anthracnose development, reducing lesion diameter from 37.67 ± 1.53 mm to 10.33 ± 1.53 mm. The enhanced interfacial adhesion enabled the coating to maintain a stable barrier and sustained bioactivity during storage, thereby improving preservation performance. This work demonstrates that constructing a metal-phenolic coordination network is an effective strategy for strengthening coating-fruit interfacial adhesion, offering a promising approach for designing high-performance edible coatings for postharvest fruit preservation.