Chitosan-based Illicium verum Hook. f. essential oil nanoemulsion as an edible coating for shelf-life enhancement of custard apple.

The present study aims to encapsulate Illicium verum essential oil (IVEO) into chitosan nanoemulsion (IVNPs) using different ratios of chitosan: IVEO (1:0, 1:0.2, 1:0.4, 1:0.6, 1:0.8, 1:1) through the ionic gelation approach and evaluate its efficacy as a novel coating agent with a unique delivery system to protect custard apples from fungi-mediated post-harvest biodeterioration and to enhance their shelf-life. The chitosan nanoemulsion and IVNPs were characterized using SEM, AFM, and DLS to observe their morphology, mean particle size, and polydispersity index. The results showed spherical nanocapsules with a uniform distribution. FTIR and XRD analysis showed effective loading of IVEO into IVNPs. The antifungal efficacy of IVEO against Aspergillus flavus (AFLHP-C3), A. luchuensis, A. niger, Fusarium chlamydosporum, Penicillium expansum, Colletotrichum acutatum, Curvularia lunata, and mycelia sterilia was enhanced after its encapsulation into the chitosan biomatrix (MIC values recorded as 0.1, 0.7, 0.8, 0.2, 0.8, 0.4, 0.25, 0.2 μL/mL, respectively). The fungal plasma membrane was detected as a potential target site of IVNPs. Furthermore, IVNPs coating (1:1) was able to preserve the rate of weight loss, pH, titrable acidity, total soluble solids, phenolic content, antioxidant capacity (p < 0.05), and sensorial attributes of custard apples during post-harvest storage, thereby acting as a novel coating agent.