Mouldy fruits and vegetables as a source of mycotoxins: part 1

Species of Aspergillus, Penicillium and Alternaria are major contributors to fruit and vegetable decay and to mycotoxin production during various stages of pathogenesis. The mycotoxins most commonly associated with fruits and vegetables and their products are aflatoxins, patulin, ochratoxin A and Alternaria toxins. Naturally occurring aflatoxins are found in fruits of tropical and subtropical regions where environmental conditions support growth of aflatoxigenic aspergilli. Aflatoxins in figs and dates have been associated with Aspergillus flavus and A. parasiticus, ochratoxin A in figs has been related mainly to A. alliaceus, and ochratoxin A in wines and other grape-based products has been associated with A. carbonarius and, to a lesser extent, with A. tubingensis and A. niger. Human exposure to patulin is primarily via apple-based products, following fruit infection by Penicillium expansum. Attention has been drawn to patulin contamination in infant apple products, and in organic fruits versus conventional ones. Alternaria species, which naturally attack a wide range of harvested fruits and vegetables, are capable of producing several mycotoxins during pathogenesis. The major mycotoxins include alternariol, alternariol methyl ether, altenuene, tenuazonic acid, and altertoxin-I. Although A. alternata is regarded as the major producer of Alternaria mycotoxins, other species, such as A. citri, A. longipes, A. tenuissima, A. arborescens, may also produce these mycotoxins. Mycotoxin accumulation in fruits and vegetables may occur in the field, and during harvest, postharvest and storage. Factors affecting mycotoxin production include the fruit or vegetable type and cultivar, geographical location, climate, pre-harvest treatments, method of harvest, postharvest treatments and storage conditions. Considering geostatistics, knowledge of the ecology of the fungi, data on crop distribution and meteorological conditions, risk predicting maps have recently been drawn. The methodologies of detection and determination of mycotoxigenic moulds and of ochratoxin A in grape products, of patulin in apple products and of Alternaria mycotoxins in fruit and vegetable products, are summarised and discussed. The present review is based on the multi-author book 'Mycotoxins in Fruits and Vegetables' published by Elsevier (2008).