Toxic aspergilli from pistachio nuts

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Abstract
Pistachio nut samples taken during various stages of development from orchards in Iran, showed that contamination with fungi occurred mainly during the later stages of nut development. Members of the genera Aspergillus and Penicillium occurred most frequently. Of the Aspergilli, the species A. niger, A. flavus and A. fischeri var. spinosus occurred most frequently, followed by A. terreus, A. tamarii and A. nidulans. Twenty-two isolates comprising 13 species were tested for toxicity to ducklings. Isolates of known toxic fungi included A. flavus, A. niger, A. parasiticus, A. ochraceus, A. versicolor, A. nidulans and A. terreus. The toxicity of A. fischeri var. spinosus is reported. Chemical analysis showed that all isolates of A. flavus and A. parasiticus produced aflatoxin B1, the isolates of A. versicolor and A. nidulans produced sterigmatocystin while the toxic isolate of A. ochraceus did not produce ochratoxins. Toxic fungi have been shown to occur in a variety of nuts (4), (5), (11), (12), (13), (15), (18), (20), (21). Aflatoxin contamination of pistachio nuts has been reported and has in the past led to the rejection of consignments of Iranian pistachio nuts (1). In Iran, pistachio nuts are produced mainly in the south eastern provinces (Kerman & Zahedan) and to a limited extent in the Northern part (Kazvin & Damghan). In 1975 it was estimated (7) that there were some 24 million pistachio trees in Iran, of which 60% were situated in Rafsanjan, Kerman (Table 1). Economic considerations as well as the potential health hazard posed by aflatoxin-contaminated nuts, prompted the University of Isfahan to initiate a study of various aspects of the mycotoxin problem in pistachio nuts.