Structure-function relationships in chitosan films containing ZIF-8-confined Ligusticum jeholense essential oil: pH-triggered release and apple ring rot control.

Abstract

Postharvest apple ring rot caused by Botryosphaeria dothidea remains difficult to control due to the poor aqueous compatibility and rapid volatilization of volatile essential oils. We engineered a chitosan (CS) film embedding Ligusticum jeholense essential oil within zeolitic imidazolate framework-8 (LEO@ZIF-8) to achieve sustained antifungal release. TEM/SEM, FT-IR, XRD, and XPS confirmed high LEO loading (65.5%) and encapsulation efficiency. LEO@ZIF-8 demonstrated pH-responsive release, with 82.6% at pH 5.0. In vitro, LEO@ZIF-8 inhibited B. dothidea more effectively than free LEO (64.6% vs. 50.6% at 62.5 nL/mL). On detached apples, LEO@ZIF-8/CS film improved hydrophobicity, enhanced microstructural homogeneity, and delayed lesion formation. It reduced weight and firmness loss, retained soluble solids, and decreased oxidative stress markers (DPPH, SOD, MDA). ZIF-8 stabilized LEO and enabled controlled release, while CS provided antimicrobial support, demonstrating LEO@ZIF-8/CS as an effective active-packaging solution for long-term fruit preservation, offering a sustainable approach to postharvest disease control.