Distribution of aflatoxins and fumonisins in dry-milled maize fractions

Abstract

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 µg kg⁻¹, respectively; the second (maize 2) had corresponding levels of 91.1 and 8841 µg 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 µg kg⁻¹) was below the European Union AFB₁ limit of 5 µg kg⁻¹ for unprocessed maize, but among the final products only coarse flour (1.7 µg kg⁻¹) was within the European Union limit of 2 µg kg⁻¹, while grits and fine flour showed higher levels (2.7 and 2.5 µg 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.