Distribution of aflatoxins and fumonisins in dry-milled maize fractions

The aim was to evaluate the distribution of aflatoxins and fumonisins in fractions derived from the dry-milling of contaminated maize. Two maize lots with different contamination levels were processed and sampled: the first (maize 1) had aflatoxin B(1) (AFB(1)) and fumonisin B(1) (FB(1)) levels of 3.6 and 5379 microg kg(-1), respectively; the second (maize 2) had corresponding levels of 91.1 and 8841 microg kg(-1), respectively. The cleaning step reduced AFB(1) and FB(1) levels by 8 and 11% in maize 1 and by 57 and 34% in maize 2. The subsequent removal of bran and germ led to a further decrease in contamination levels in the products destined for human consumption. In the latter, AFB(1) was uniformly distributed, while FB(1) was concentrated in the finer size fractions. Contamination of raw maize 1 (3.6 microg kg(-1)) was below the European Union AFB(1) limit of 5 microg kg(-1) for unprocessed maize, but among the final products only coarse flour (1.7 microg kg(-1)) was within the European Union limit of 2 microg kg(-1), while grits and fine flour showed higher levels (2.7 and 2.5 microg kg(-1), respectively). As regards cleaned maize, a different distribution of the two toxins was observed in the kernels: AFB(1) contamination was more superficial and concentrated in germ, while FB(1) contamination affected the inner layers of the kernels.