Chemical Degradation of Aflatoxin Contaminants in Maize as a Value Addition Strategy for Selected Counties in Kenya

Abstract

Aflatoxin contamination of maize, rice, groundnuts and wheat products is a common phenomenon in Kenya. This result to low nutritional value and huge economic loss of the crops produced. Additionally, consumption of aflatoxin contaminated cereals and nuts above 10 μg/kg can lead to chronic health effects in humans, hence the products are usually destroyed. This study sought to assess aflatoxin prevalence in Busia, Migori, Trans-Nzoia, Nakuru, Nairobi, Kajiado, Machakos, Makueni, Embu and Isiolo counties in Kenya, determine the socio-economic impact and value addition to aflatoxin contaminated maize by use of different chemicals. Structured questionnaires were used to assess the prevalence and socio-economic impact caused by aflatoxin contamination of maize handlers along the value chain from different regions. Aflatoxin B1, B2, G1 and G2 residues in the samples were extracted using 22.7 % methanol and screened by enzyme-linked immunosorbent assay. Confirmatory and characterization tests were done using high performance liquid chromatography equipped with a fluorescence detector. Degradation potential of aflatoxin in maize was conducted using sodium hydrogen sulfite, ferulic acid, ammonium carbonate, sodium hydrogen carbonate and sodium hypochlorite on whole, dehulled and ground maize, catalyzed by hydrogen peroxide, ammonia and methylamine. Ninety-four (94) percent of the maize samples were contaminated with aflatoxins, of which 59.6 % had levels above the East Africa tolerable limit of 10 μg/kg. The mean concentration of aflatoxins ranges was 10.54±1.52 to 50.08±4.42 μg/kg in eastern, 2.65±0.32 to 9.36±0.97 μg/kg in western, 1.90±0.11 to 8.74±0.54 μg/kg in Nairobi, and 0.95±0.05 to 4.37±0.27 μg/kg in Rift valley. The Spearman rank correlation test for aflatoxins B1, B2, G1 and G2 showed a strong correlation > 0.75, while the Scheirer Ray Hare test showed statistically significant levels of the four aflatoxins at p < 0.05. Sodium hypochlorite achieved the highest degradation of aflatoxins on whole, de-hulled and ground maize samples ranging from 88.2 to 98.1 %. Ethanol yield from aflatoxin stripped maize was 34.7 % while contaminated maize registered 29.2 % yield. Variances in aflatoxin contamination load across the regions can be attributed to differences in microclimates, handling, environment and maize seeds factors. The results suggest high prevalence of aflatoxin contamination in maize from the 11 counties, which need to be managed to reduce the human health risks. The maize products decontaminated of aflatoxin formed useful raw material for industrial ethanol and briquettes production. There is a need for stakeholders to prioritize cereal crop irrigation, fertilizer management, plant inspection, and pest and disease control to reduce phyto-immunity stresses on maize and post-harvest losses associated with aflatoxin contamination.