Synergistic antifungal properties of lauraldehyde and geraniol against Aspergillus flavus in pistachio

Natural plant-derived compounds have been recognized as promising fungicides for reducing Aspergillus flavus growth in agricultural commodities. In this study, the synergistic antifungal activity of plant-derived compounds against A. flavus growth in stored pistachios was investigated. The minimum inhibitory concentration (MIC) of lauraldehyde, geraniol, dihydrocoumarin, and p-anisaldehyde against A. flavus in potato dextrose broth (PDB) were 0.40, 0.20, 0.40, and 0.80 mg/mL, respectively. Whereas, after screening 6 groups of agents using the checkerboard method, only one combination, i.e., that of lauraldehyde and geraniol (SLG), showed synergistic effect (fractional inhibitory concentration index = 0.5) on A. flavus. In addition, at 2 MIC, SLG completely inhibited the spore germination of A. flavus, colony radial growth, and aflatoxin biosynthesis. At the same time, the mycelial growth was inhibited by more than 98%. Further research found that fumigation with SLG significantly inhibited the growth of A. flavus in stored pistachios and reduced aflatoxin biosynthesis. Moreover, the pistachios with SLG fumigation exhibited higher soluble protein content, lower malonaldehyde (MDA) content, and lower carbonyl values, indicating that fumigation with SLG could effectively delay the trend of quality deterioration in stored pistachios. These results supported SLG as a potential green antifungal agent for the shelf-life extension of stored pistachios.