We have summarized the results of the examinations for aflatoxins (AFs) conducted from 2002 to 2006 in approximately 2,300 to 3,000 annual samples of raw peanuts imported to Japan from major exporting countries. In peanuts from China, South Africa, the U.S. and Paraguay, a comparison was made between the proportion of products in which AFB
1 and/or B
2 was detected and that of products in which AFB
1, B
2, G
1 and/or G
2 was detected during the five years of survey. We also calculated the proportions of samples showing AF levels above the Japanese regulatory value (10 ppb for AFB
1 only) and those showing levels above the international limit (a total of 15 μg/kg [ppb] for B- and G-group AFs) to all samples examined during the same survey period. The results showed that, in the Chinese peanuts which had large sample sizes, the proportion of products having AFB
1 levels above the AFB
1-focused regulatory value (0.4 % to 0.8 %) and that of products having AF levels above the limit of total B- and G-group AFs (0.4 % to 1.1 %) were very similar. Similarly, in South African peanuts, 0.3 % to 1.0 % and 0.3 to 1.2 % of the products showed AF levels above the AFB
1-focused limit and the AF B- and G-group total limit, respectively. Isolates of
Aspergillus section
Flavi (the cause of AF contamination) from peanuts were identified for morphology and AF and cyclopiazonic acid productivity, and by heteroduplex panel analysis (HPA). It was found that the contamination of Chinese samples by B- and G-group AFs was caused mainly by
A. parasiticus, whereas isolates from South African samples contaminated by B- and G-group AFs included, in addition to
A. parasiticus, an atypical
A. flavus isolate which forms numerous small sclerotia and produces B- and G-group AFs. This isolate was categorized into AfF4 by HPA of section
Flavi.
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