Active chitosan coating to inhibit decay and maintain mango postharvest quality.

BACKGROUND

Microbial decay limits the storage, quality and trade of mangoes (Mangifera indica). We developed an active chitosan coating containing zinc oxide nanoparticles (ZnO-NPs) and Eucalyptus radiata essential oil (EEO) to inhibit decay and preserve postharvest quality of mango. Chitosan (cationic) can disrupt microbial membranes; ZnO-NPs act mainly via reactive-oxygen-species generation and Zn2+ interactions; EEO (rich in oxygenated monoterpenes) perturbs lipid bilayers, offering complementary antimicrobial actions.

RESULTS

In vitro, the developed coating achieved 97.28% inhibition of Lasiodiplodia theobromae mycelial growth (plate assay) and yielded the lowest MIC/MBC values against Staphylococcus aureus and Escherichia coli. In vivo, for 'Tommy Atkins' mangoes stored at 9 °C for 28 days, coated fruit retained higher firmness (7.30 N versus 3.42 N, P ≤ 0.05), showed smaller skin colour changes and exhibited a 7-day delay in the respiratory peak. Postharvest decay severity in coated fruit was reduced by ca 64.3%, compared to uncoated fruit. The developed coating resulted in the lowest AUDPC (17.9) against anthracnose.

CONCLUSION

The synergistic action of chitosan, ZnO-NPs and EEO enhanced antimicrobial efficacy and preserved postharvest quality, reducing decay and the need for synthetic fungicide application on mango. The coating can be integrated after sanitisation and before packing, and is compatible with cold-chain logistics at 9 °C. These outcomes support longer distribution windows and improved market access for the mango industry. © 2025 The Author(s). Journal of the Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.