Natural flavour (E,E)-2,4-heptadienal as a potential fumigant for control of Aspergillus flavus in stored peanut seeds: Finding new antifungal agents based on preservative sorbic acid

Strategies for preventing the growth of mycotoxigenic fungi in agricultural commodities need to be identified. In this study, sorbaldehyde and (E,E)-2,4-heptadienal, two natural aldehydes as derivatives of the common food preservative sorbic acid, were investigated for their antifungal efficacy as fumigants against Aspergillus flavus in stored peanut seeds. In vitro assays demonstrated that both sorbaldehyde and (E,E)-2,4-heptadienal exhibited stronger inhibitory effects on A. flavus than sorbic acid. Moreover, the vapor phase of these two aldehydes were much more effective than direct contact on A. flavus growth. (E,E)-2,4-Heptadienal showed higher fumigant activity than sorbaldehyde, with 50% effective concentration (EC50) values of 1.5 and 2.6 mg/l air, and minimum inhibitory concentration (MIC) values of 16 and 8 mg/l air, respectively. Furthermore, fumigation with sorbaldehyde or (E,E)-2,4-heptadienal could significantly reduce and delay A. flavus growth in stored peanut seeds, and the infection was completely inhibited by 100 mg/l air sorbaldehyde or 75 mg/l air (E,E)-2,4-heptadienal. These results revealed that (E,E)-2,4-heptadienal, a natural food flavour with better safety than sorbaldehyde, has high potential as an antifungal fumigant for protecting peanut seeds from contamination of A. flavus during storage.