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 B1 (AFB1) and fumonisin B1 (FB1) levels of 3.6 and 5379 g kg-1, respectively; the second (maize 2) had corresponding levels of 91.1 and 8841 g kg-1, respectively. The cleaning step reduced AFB1 and FB1 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, AFB1 was uniformly distributed, while FB1 was concentrated in the finer size fractions. Contamination of raw maize 1 (3.6 g kg-1) was below the European Union AFB1 limit of 5 g kg-1 for unprocessed maize, but among the final products only coarse flour (1.7 g kg-1) was within the European Union limit of 2 g kg-1, while grits and fine flour showed higher levels (2.7 and 2.5 g kg-1, respectively). As regards cleaned maize, a different distribution of the two toxins was observed in the kernels: AFB1 contamination was more superficial and concentrated in germ, while FB1 contamination affected the inner layers of the kernels.