Quality of imported buckwheat and wheat with reference to fungal infection and mycotoxin contamination

Abstract

To evaluate the safety of imported cereals in 1988 for mycotoxin contamination, the survey of 18 samples of buckwheat from the U.S.A., Canada and China, and 20 samples of wheat from the U.S.A. and Canada was carried out on mycotoxin analyses (aflatoxins for the buckwheat, and nivalenol and deoxynivalenol for the wheat, respectively), fungal infection, germinability and water activity (a_w). None of the buckwheat samples showed aflatoxin contamination, but 8 samples of the wheat were positive for nivalenol and/or deoxynivalenol with the levels of trace to 40 μg/kg. Major isolates of fungi from the buckwheat and the wheat samples were Alternaria spp. as one of the common field fungi. Only a few storage fungi such as Eurotium spp. and Aspergillus flavus (non-aflatoxigenic) were detected but the level of their frequency occurrence was very low. The a_w ranges of the samples were 0.4 to 0.7, mostly less than a_w minima (0.65-0.70) for growth of the common storage fungi. Results of these examinations substantiate the need for : (1) implementing a routine moni-taring system for the Fusarium toxins in imported cereals, especially in wheat, and (2) properly controlling water contents of the post-imported cereals.