Effect of Crosslinking on the Physical Properties and Antifungal Activity of Active Coatings Containing Cinnamon Essential Oil for Anthracnose Control in Mangoes

Abstract

This study aimed to verify the stability of cinnamon essential oil (CEO) nanoemulsions after their incorporation into polymer-based coatings for the control of anthracnose in mangoes. A 0.75% CEO emulsion with Tween 80 was produced via ultrasonication and incorporated into sodium alginate (1%) and carboxymethylcellulose (0.5%) solutions, with or without calcium-induced crosslinking. Physical stability (droplet size, polydispersity index, zeta potential, pH, whiteness, turbidity, and antifungal activity) was monitored over 28 days. Furthermore, the rheological behavior and efficacy of the active coatings were evaluated on mangoes artificially inoculated with Colletotrichum gloeosporioides. Crosslinked formulation showed lower variations in droplet size and PDI over time, indicating greater protection of CEO droplets within the structured polymeric network. All coating-forming solutions exhibited pseudoplastic behavior; however, the incorporation of the nanoemulsion reduced viscosity compared with the base coating while maintaining adequate flow behavior for brush application. Notably, the crosslinked coating achieved a substantial mitigation of the disease, reaching up to 70% reduction in anthracnose lesion progression of the mangoes. Therefore, calcium crosslinking resulted in better long-term maintenance of physicochemical and functional properties, confirming the efficiency of this strategy in enhancing the performance of CEO-based active coatings for sustainable postharvest disease management.