Detection and quantification of aflatoxin in cassava and maize flour sold in Kigali open markets, Rwanda

Maize and cassava flour are raw materials and/or ingredients for a variety of food products, which are eaten in Rwanda by all age groups including weaning-age children. Unsafe cassava and maize flour derived products may thus affect the health of a high number of Rwandan populations. The aim of the current study was to detect and quantify aflatoxins in cassava and maize flour. The samples were collected from 5 open markets in Kigali city and analyzed for aflatoxin B1, B2, G1 and G2 by using High Performance Thin Layer Chromatography. In all the cassava flour samples, aflatoxins analyzed were below the limit of detection (0.15 ppb, 0.2 ppb, 0.2 ppb and 0.5 ppb for aflatoxin B1, B2, G1 and G2, respectively). Unlike cassava flour, maize flour was contaminated with aflatoxins at detectable levels. The highest contamination was with aflatoxin B1 contaminating 40% of the samples analyzed, with the maximum content of 15.62 ppb. Aflatoxin B1 was higher in 13% of the maize flour samples than the maximum tolerable Codex Alimentarius Commission limit (5 ppb) adopted by national food regulation body (Rwanda Standards Board). The least contamination of maize flour was with aflatoxin G2 that contaminated 7% of the samples analyzed, with the content varying from not detected to 2.42 ppb. It was concluded from the findings of the current study that maize flour might be more unsafe to consumers than cassava flour. These differences in aflatoxins contamination between cassava and maize flour may be due to either variation in their chemical composition, in resistance to fungal invasion or differences in handling practices and processing operations during the production chain of these two food commodities. Further research work would be necessary to elucidate factors determining differences in aflatoxins contamination between cassava flour and maize flour. Meanwhile it would be suggested to Rwanda Standards Boards and other stakeholders to continue their efforts in assuring safety of maize flour in abide to protect the health of a large number of consumers who rely on maize flour derived products for their daily life.