Trans-2-hexenal/β-cyclodextrin effectively reduces green mold in citrus fruit

Green mold, caused by Penicillium digitatum , is the primary postharvest disease in citrus fruit. Trans -2-hexenal was found to exert a considerable inhibitory effect on the mycelial growth of P. digitatum with a minimum fungicidal concentration (MFC) of 0.106 g L −1 . To overcome its hydrophobic restriction, a trans -2-hexenal- β -cyclodextrin inclusion complex ( β -CDIC) was prepared by the saturated aqueous solution method. In vitro assays revealed that the MFC of β -CDIC for P. digitatum mycelial growth was 1.00 g L −1 , and 10.0 g L −1 β -CDIC apparently reduced the incidence of green mold in citrus fruit inoculated with P. digitatum while maintaining fruit quality. The structure of β -CDIC was characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), fourier transform-infrared spectroscopy (FT-IR), thermogravimetric (TG), and nuclear magnetic resonance (NMR) analyzes. The results showed that the H-1 proton of trans -2-hexenal correlated with the H-5′ proton of β -cyclodextrin ( β -CD), which was further confirmed by molecular docking analysis. The present study suggests that β -CDIC is a promising candidate for controlling postharvest diseases in citrus fruit.