Natural postharvest aflatoxin occurrence in food legumes in the smallholder farming sector of Zimbabwe

ABSTRACT

Aflatoxins, mainly produced by Aspergillus flavus and Aspergillus parasiticus, are highly toxic and may lead to health problems such as liver cancer. Exposure to aflatoxins may result from ingestion of contaminated foods. Levels of AFB₁, AFB₂, AFG₁ and AFG₂ in samples of groundnuts (Arachis hypogaea), beans (Phaseolus vulgaris), cowpeas (Vigna unguiculata) and bambara nuts (Vigna subterranean) grown by smallholder farmers in Shamva and Makoni districts, Zimbabwe, were determined at harvesting, using high performance liquid chromatography after immunoaffinity clean-up. Aflatoxins were detected in 12.5% of groundnut samples with concentrations ranging up to 175.9 µg/kg. Aflatoxins were present in 4.3% of the cowpea samples with concentrations ranging from 1.4 to 103.4 µg/kg. Due to alarming levels of aflatoxins detected in legumes versus maximum permissible levels, there is a need to assist smallholder farmers to develop harvest control strategies to reduce contamination of aflatoxins in legumes.

KEYWORDS:

• Aflatoxins
• Aspergillus flavus
• Aspergillus parasiticus
• groundnuts
• beans
• bambara nuts
• cowpeas

Acknowledgements

We thank the farmers of Makoni and Shamva districts for providing the grain samples used in this study. We are also grateful to the field agricultural extension staff for their technical support in legume grain sample collection. Technical staff of the University of Zimbabwe are acknowledged for their support. We thank Action Contrela Faim and International Rescue Committee for helping in grain collection logistics. This study was supported by International Development Research Centre - Canada, Australian Centre for International Agricultural Research and Australian International Food Security Research Centre [Grant No. 107838].

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the International Development Research Centre – Canada, Australian Centre for International Agricultural Research and Australian International Food Security Research Centre [grant number 107838].