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

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.

Aflatoxins: Production, Structure, Health Issues and Incidence in Southeast Asian and Sub-Saharan African Countries

“…Recent data suggest that that the situation did not improve since then and the dietary exposure to aflatoxins remains too high. The probable daily intake (PDI) of aflatoxin B1 in the country, via maize only, was recently estimated to vary between 0.07-60,612.00 ng/kg bw/day, with an average of 312.4 ng/kg bw/day) [80], which is alarming compared with an average of 10 to 200 ng/kg/day for the rest of the world [81], and with the conservative tolerable daily intake (TDI) of 0.11 to 0.19 ng/kg bw/day [82]. Incidentally, this country also ranks among the countries with the highest prevalence of oesophageal cancer, which was associated with aflatoxin intake as a risk factor [18,80,83].…”

“…The probable daily intake (PDI) of aflatoxin B1 in the country, via maize only, was recently estimated to vary between 0.07-60,612.00 ng/kg bw/day, with an average of 312.4 ng/kg bw/day) [80], which is alarming compared with an average of 10 to 200 ng/kg/day for the rest of the world [81], and with the conservative tolerable daily intake (TDI) of 0.11 to 0.19 ng/kg bw/day [82]. Incidentally, this country also ranks among the countries with the highest prevalence of oesophageal cancer, which was associated with aflatoxin intake as a risk factor [18,80,83]. Conversely, a recent survey on aflatoxin contamination of maize grown in eight different AEZs in Uganda revealed that the highest levels (a maximum of 3760 g/kg) and an average of 66.5 g/kg) were recorded in the zones with high rainfalls (1200->1400 mm); the percentage of samples exceeding the national regulatory standards of 10 g/kg reached 22.2% [84].…”

“…In fact, there is a multiplicity of factors that interfere with the effect of the climate type at different production stages from plant development to crop storage [18,62]. It is increasingly recognized that management systems with rigorous implementation of the good agricultural practices (GAPs) and farmer trainings are critical measures to mitigate the incidence of aflatoxins in agricultural products regardless of the climate type [18,67,80,[97][98][99]. The implementation of such measures in South Africa in the framework of a project on the "Adaptation of agricultural practices to climate change in Sub-Saharan Africa (CAADP)" aimed at "good agricultural adaptation practices" [100], appears to have been successful in controlling aflatoxin contamination.…”

“…In view of the above-mentioned limitations of conventional and innovative decontamination methods, there is a general agreement that for these strategies to ensure sustainable protection against aflatoxin contamination, they must be a part of an integrated approach using appropriate quality assurance systems. Such an approach should encompass pre-and post-harvest measures, selection of mold-resistant cultivars, proper use of fungicides and insecticides, adoption of specific cultural techniques depending on the AEZ and increased awareness of the farmers' regarding the impact of mycotoxin contamination on the crop yield and health [1,80,208]. Among the various actions of this wholistic approach to improve the situation in endemic zones, there is a clear trend to alter the soil microbiome by artificial establishment of non-aflatoxigenic molds strains.…”

Mapping Quantitative Trait Loci Associated With Resistance to Aflatoxin Accumulation in Maize Inbred Mp719

“…Pre-harvest management is a critical practice for minimizing aflatoxin contamination of maize (Mahuku et al, 2019). Resistance to aflatoxin accumulation can be achieved by reducing the fungal infection in the grain, reducing the amount of toxin produced by the fungus, or both (Warburton et al, 2011).…”