A survey of the incidence and level of aflatoxin contamination in a range of locally and imported processed foods on Malawian retail market

Samples of locally (Malawian) processed and imported maize- and groundnut-based food products (peanut butters, roasted groundnuts, peanut based therapeutic foods, instant baby cereals, maize puffs and de-hulled maize flour) were collected from popular markets of Lilongwe City, Malawi. The samples were analysed in order to determine the frequency and extent of aflatoxin contamination, using immuno-affinity column and reversed-phase liquid chromatography with post-column photochemical derivatization and fluorescence detection. No aflatoxins were detected in all samples of imported baby cereal and locally processed de-hulled maize flour. However, all locally processed maize based baby foods had aflatoxins above EU maximum tolerable level of 0.1 μg/kg. In 75% of locally processed maize puffs, aflatoxins were detected at levels of up to 2 μg/kg. Peanut based therapeutic foods had aflatoxin level between 1.6 and 2.9 μg/kg, exceeding the EU tolerable maximum level (0.1 μg/kg) set for food for health purposes. Locally processed peanut butters had aflatoxins levels in the range of 34.2-115.6 μg/kg, which was significantly higher than their imported counterparts (<0.2-4.3 μg/kg). Samples of locally processed skinned and de-skinned roasted groundnuts had aflatoxins in range of 0.5-2.5 μg/kg and 0.6-36.9 μg/kg, respectively. These results highlight the need for rigorous monitoring of aflatoxins in commercially available processed products in order to reduce likely health risks associated with dietary aflatoxin intake.