Antifungal efficacy and fumigation potential of octanal and (E)-2-octenal against Aspergillus flavus in stored peanut seeds

Abstract

Developing novel methods to safely and effectively prevent mycotoxigenic fungi contamination in agricultural products is critical for protecting food security and human health. The present study investigated the effectiveness of two naturally occurring compounds, octanal and (E)-2-octenal, in controlling Aspergillus flavus contamination in peanut seeds. In vitro tests demonstrated that octanal and (E)-2-octenal exhibited superior antifungal efficacy compared to sorbic acid and that their fumigation effects were significantly more potent than their direct contact inhibitory effects. Octanal and (E)-2-octenal as fumigants could strongly inhibited the growth of A. flavus with the minimum inhibitory concentrations (MIC) of 0.032 and 0.016 g/l air, and minimum fungicidal concentrations (MFC) of 0.04 and 0.02 g/l air, respectively. The results of in vivo tests showed that fumigation with octanal and (E)-2-octenal significantly suppressed the growth of A. flavus in peanut seeds, and (E)-2-octenal fumigation exhibited higher efficacy, preventing the growth of A. flavus in peanut seeds over a 14-day incubation period, with MIC and MFC values 0.8 and 2.5 g/l air, respectively. Notably, after 24 h fumigation with octanal and (E)-2-octenal at 3.5 g/l air, the peanut seeds were exposed to ambient air for 5 days, and still exhibited complete resistance to infection by artificially inoculated A. flavus, revealing that pre-fumigation treatment enabled peanut seeds to resist A. flavus infection within a specific storage period. These findings indicated that octanal and (E)-2-octenal can be used as efficient antifungal fumigants with the potential to protect peanut seeds from A. flavus infection during storage.