Chitosan/mandarin essential oil-based films on citrus fruits for the control of the medfly attack and to prevent the occurrence of grey and blue mould in post-harvest

Citrus fruits, widely consumed around the world, can be negatively affected by pests and fungal infections during their cultivation, handling, transportation, and storage, thus resulting in substantial yield losses and food waste. The use of natural preservatives like chitosan (CHT) and essential oils (EOs) is a promising approach for reducing chemical inputs to preserve food products. This study investigated the effects of CHT, extracted from crab shells and the fungus Pleorotus ostreatus, alone and in combination with mandarin (Citrus × reticulata Blanco, Rutaceae) essential oil (MEO), as an oviposition deterrent towards Ceratitis capitata (Diptera: Tephritidae), the Mediterranean fruit fly, and growth inhibitor of Penicillium (P. expansum, P. digitatum, and P. italicum) spp. fungi, the causal agents of apple and citrus rot. A solution of 1.0% CHT of both origins (from crab shells and P. ostreatus) added with MEO resulted as the best combination to significantly reduce the oviposition percentage of C. capitata as well as mycelial growth and spore germination of Penicillium isolates and their pathogenic activity on Citrus japonica Thunb. (kumquats) fruits. According to results here collected, CHT added with MEO represents a valid combination to be used as an edible film and coating as part of an integrated control strategy to improve the shelf-life of fresh citrus fruits. Furthermore, fungal CHT, here used for the first time in combination with MEO, can be an excellent alternative to reply to the eating habits and necessities of the final consumers. •Chitosan (CHT) of different origins was combined with mandarin essential oil (MEO).•We used CHT solutions from crab shells and the fungus Pleurotus ostreatus.•CHT + MEO inhibited mycelium and spore germination of Penicillium spp.•CHT + MEO protected kumquat fruit against the oviposition by Ceratitis capitata.•CHT of both origins + MEO could be valid tools in kumquats' post-harvest protection.