From Antifungal Potency to Fruit Protection: Infection-Site Bioavailability and Delivery Constraints in Antifungal Edible Coatings

Postharvest anthracnose caused by Colletotrichum spp. remains a constraint to the storage and marketing of tropical and subtropical fruits. Edible antifungal coatings carrying biopolymers and antifungal agents have received considerable attention as alternatives to conventional fungicides. Previous research has demonstrated the potential of biopolymers, essential oils, biocontrol agents, nanoemulsions, Pickering emulsions, multilayer coatings, and delivery systems. However, strong inhibition of mycelial growth or conidial germination in vitro does not consistently translate into equivalent disease control on fruit, indicating that intrinsic antifungal potency alone is insufficient to explain postharvest performance. Colletotrichum conidia are initially exposed at the fruit surface, but appressorium formation, cuticle penetration, and quiescent colonization progressively separate the pathogen from surface-applied actives. Meanwhile, fruit cuticles vary among hosts and cultivars and continue changing during storage. Temperature, relative humidity, condensation, ripening, and handling further influence infection and coating properties, while active physicochemical processes determine antifungal retention, partitioning, volatilization, and release. This review examines and compares edible antifungal coatings through infection-site bioavailability, integrating pathogen stage, fruit-surface transport, storage trajectory, active properties, and coating architecture to explain the in vitro–to-in situ translation gap and define context-matched design and measurement priorities.