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Uncommon occurrence ratios of aflatoxin B1, B2, G1, and G2 in maize and groundnuts from Malawi

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Abstract

We report an unusual aflatoxin profile in maize and groundnuts from Malawi, with aflatoxin G1 found routinely at equal or even higher levels than aflatoxin B1. Aflatoxin B1 (AFB1) ratio in a contaminated sample is generally greater than 50 % of total aflatoxin (sum of aflatoxin B1, B2, G1, and G2). In Malawi, the aflatoxin occurrence ratios were determined by examining LC-MS/MS and HPLC fluorescence detection (FLD) data of 156 naturally contaminated raw maize and 80 groundnut samples collected in 2011 and 2012. Results showed that natural aflatoxin occurrence ratio differed. In 47 % of the samples, the concentration of AFG1 was higher than that of AFB1. The mean concentration percentages of AFB1/AFB2/AFG1/AFG2 in reference to total aflatoxins were found to be 47:5:43:5 %, respectively. The AFG1 and AFB1 50/50 trend was observed in maize and groundnuts and was consistent for samples collected in both years. If the AFB1 measurement was used to check compliance of total aflatoxin regulatory limit set at 10, 20, 100, and 200 μg/kg with an assumption that AFB1 ≥ 50 % of the total aflatoxin content, 8, 13, 24, and 26 % false negative rates would have occurred respectively. It is therefore important for legislation to consider total aflatoxins rather than AFB1 alone.

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Acknowledgments

The authors are grateful for the following: (1) the Federal Country Lower Austria and the European regional development fund of the European Union for the LC-MS/MS system at IFA-Tulln; (2) the donation of HPLC system and starter-park reagents by EU to the Dept. of Agricultural Research Services (Malawi) through a SADC-Food Safety Capacity Building on Residues Control Project; (3) the Republic of Malawi (Ministry of Agriculture and Food Security), the World Bank, and the Norwegian Ministry of Foreign Affairs for co-financing the first author’s travel costs and living expenses abroad; (4) Prof. Dr. Maurice Monjerezi of the University of Malawi for kindly designing a map depicting sampling sites; and (5) invaluable technical assistance provided by L. Singano, T. Mhango, H. Mbalame, C. Gadaga, D. Kalima, D. Bwanamiri, M. Kalitsiro, C. Tchuwa

Conflict of interest

The authors declare that there is no conflict of interest.

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Authors and Affiliations

  1. Faculty of Pharmaceutical Sciences, Department of Bioanalysis, Ghent University, Ottergemsesteenweg 460, 9000, Ghent, Belgium

    Limbikani Matumba, Emmanuel Njumbe Ediage, Christof Van Poucke & Sarah De Saeger

  2. Center for Analytical Chemistry, Department for Agrobiotechnology (IFA-Tulln), University of Natural Resources and Life Sciences, Vienna (BOKU), Konrad Lorenz Str. 20, 3430, Tulln, Austria

    Michael Sulyok & Rudolf Krska

  3. International Crops Research Institute for the Semi-Arid Tropics ICRISAT, P.O. Box 1096, Lilongwe, Malawi

    Samuel M. C. Njoroge

  4. Department of Agricultural Research Services, Chitedze Research Station, P.O. Box 158, Lilongwe, Malawi

    Limbikani Matumba

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  1. Limbikani Matumba
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  2. Michael Sulyok
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  3. Samuel M. C. Njoroge
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  4. Emmanuel Njumbe Ediage
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  5. Christof Van Poucke
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  6. Sarah De Saeger
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  7. Rudolf Krska
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Correspondence to Limbikani Matumba.

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Matumba, L., Sulyok, M., Njoroge, S.M.C. et al. Uncommon occurrence ratios of aflatoxin B1, B2, G1, and G2 in maize and groundnuts from Malawi. Mycotoxin Res 31, 57–62 (2015). https://doi.org/10.1007/s12550-014-0209-z

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  • DOI: https://doi.org/10.1007/s12550-014-0209-z

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