Pre-harvest management is a critical practice for minimizing aflatoxin contamination of maize

George Mahuku,Henry Sila Nzioki,Charity Mutegi,Fred Kanampiu,Clare Narrod,Dan Makumbi

doi:10.1016/j.foodcont.2018.08.032

Abstract

Maize, the main dietary staple in Kenya, is one of the crops most susceptible to contamination by aflatoxin. To understand sources of aflatoxin contamination for home grown maize, we collected 789 maize samples from smallholder farmers’ fields in Eastern and South Western, two regions in Kenya representing high and low aflatoxin risk areas, respectively, and determined aflatoxin B1 (AFB1) using ELISA with specific polyclonal antibodies. AFB1 was detected in 274 of the 416 samples from Eastern Kenya at levels between 0.01 and 9091.8 μg kg−1 (mean 67.8 μg kg−1). In South Western, AFB1 was detected in 233 of the 373 samples at levels between 0.98 and 722.2 μg kg−1 (mean 22.3 μg kg−1). Of the samples containing AFB1, 153 (55.8%) from Eastern and 102 (43.8%) from South Western exceeded the maximum allowable limit of AFB1 (5 μg kg−1) in maize for human consumption in Kenya. The probable daily intake (PDI) of AFB1 in Eastern Kenya ranged from 0.07 to 60612 ng kg−1 bw day−1 (mean 451.8 ng kg−1 bw day−1), while for South Western, PDI ranged from 6.53 to 4814.7 ng kg−1 bw day−1 (mean 148.4 ng kg−1 bw day−1). The average PDI for both regions exceeded the estimated provisional maximum tolerable daily intake of AFB1, which is a health concern for the population in these regions. These results revealed significant levels of preharvest aflatoxin contamination of maize in both regions. Prevention of preharvest infection of maize by toxigenic A. flavus strains should be a critical focal point to prevent aflatoxin contamination and exposure.

Highlights

Aflatoxins are secondary metabolites produced by Aspergillus flavus and A. parasiticus fungi that are ubiquitous in many tropical soils where maize (Zea mays L.) is grown
A larger proportion of samples from both regions (72.7% for South Western and 63.2% for Eastern) contained either no detectable aflatoxin B1 (AFB1) or had AFB1 levels below 5 μg kg−1, the legal limit set by the East African Community (EAC) and the Kenyan authorities as safe for human consumption (Fig. 3)
Aflatoxin B1 levels varied between the regions with significantly higher levels (P = 0.0045) in samples from Eastern Kenya than in

Summary

Introduction

Aflatoxins are secondary metabolites produced by Aspergillus flavus and A. parasiticus fungi that are ubiquitous in many tropical soils where maize (Zea mays L.) is grown. The main dietary staple in Kenya, is one of the crops most susceptible to infection by A. flavus and contamination by aflatoxin. Contamination of maize grain with aflatoxin has been a major issue in Kenya, where average per capita consumption is 400 g of maize/day (Lewis et al, 2005). More than 75% of maize in Kenya is produced by smallholder farmers and mostly for their own consumption, and the surplus is informally traded. Under this scenario, aflatoxin contamination of home-grown maize presents a significant threat to the health of rural and urban consumers, who are dependent on maize as their staple

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Discussion

Conclusion