Inhibition of Aflatoxin‐producing Fungi by Onion Extracts

Various extractives of onion were tested for their inhibitory activity towards the growth of the aflatoxin‐producing fungi, Aspergillus flavas and A. parasiticus. Ether extract and lachrymatory factor (LF), which has been earlier identified as thiopropanal‐s‐oxide, were found to have potent antifungal activity. Steam‐distilled onion oil, which is devoid of LF, was not as potent as ether extract and LF. Its major component, dipropyldisulfide was ineffective as a fungal inhibitor. Ethyl acetate extract containing phenolics was also ineffective. Exposure of onions to gamma‐irradiation at a sprout‐inhibiting dose (6 krad) did not alter the inhibitory potency of the onion extractives which, however, appeared to be heat‐labile.