The mycotoxin potential of peanuts (groundnuts): The U.S.A. Viewpoint

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The mycotoxin potential of a plant product can be gauged by seeking answers to two of three questions basic to the mycotoxin problem; namely, ‘Which of the fungi invading the product can be toxicogenic?’, and ‘How can they become established in the product?’ Both questions relate to the quite new science of microbial synecology. In contrast, the third basic question (‘What factors are necessary for toxin production by a given toxicogenic fungus?’) relates to the much older but more complex science of microbial autecology. Fruits of Arachis hypogaea L., called ‘peanuts’ (U.S.A.) or ‘groundnuts’, are completely hypogeic in their development, and there seems to be a successional invasion of them by soil-borne or ‘field’ fungi with the result that sound mature fruits have a dormant or quiescent endogeocarpic microfloral community. Results of co-operative research in six peanut producing states (U.S.A.) and at the University of Minnesota, interpreted in the light of present-day peanut harvesting practices in the U.S.A., justify the following conclusions: (1) Aspergillus flavus can be toxicogenic under field conditions and is a serious problem. (2) Many other of the fungi from the peanut endogeocarpic community are toxicogenic under laboratory conditions. (3) Until the conditions under which such fungi may become toxicogenic are better known, their presence in lifted groundnuts constitutes a real mycotoxin potential. (4) The genera posing the greatest threat are, in estimated order of importance, Penicillium, Aspergillus (primarily because of A. flavus), Alternaria, and Fusarium. (5) Much care must be exercised with peanuts after lifting, to minimise opportunity for proliferation of such fungi. This care must be exercised at least until we determine extent to which such fungi might be expected to produce toxins in peanut fruits on the farm and during subsequent handling.