Fate of aflatoxins in cornmeal during single-screw extrusion: A bioaccessibility approach

The potential reduction of aflatoxins B1, B2, G1 and G2 levels through extrusion as well as their bioaccessibility in corn-based products were investigated. Cornmeal samples were spiked with aflatoxins (50 ng g(-1)) and extruded in the absence and presence of high-amylose corn starch (20%, w/w). Aflatoxins were quantified before and after the extrusion process, and the extruded products were subjected to in vitro digestion process where the toxin bioaccessibility was later determined. Aflatoxins quantification was done via HPLC-fluorescence detector. Extrusion of cornmeal led to a reduction of aflatoxins level (B1 - 83.7%, B2 - 80.5%, G1 - 74.7% and G2 - 87.1%), and when high-amylose corn starch was added to the formulation higher aflatoxins reductions were observed (B1 - 89.9%, B2 - 88.6%, G1 - 75.0% and G2 - 89.9%). The bioaccessibility indicates that part of aflatoxins reduction observed after the extrusion may be caused by their interactions with food matrix macromolecules, and once the digestion is completed, part of these toxins become available for absorption in the small intestine. Therefore, it is recommended to include bioaccessibility testing of cereals after thermal treatment processes used to prepare food because they can form modified mycotoxins not detectable by conventional method.