Aflatoxins: Impact on food safety

Aflatoxins were discovered in the late 1950s and early 1960’s, when scientists identified it as a causative agent of “turkey X” disease, and epidemic involving deaths of numerous turkey poults, ducklings, and chicks fed diets containing certain lots of peanut meal origination from South America (Wannop, 1963).

They are poisonous substances produced by a certain group of fungi (mould) that are found naturally all over the world; they can contaminate food crops and pose a serious health threat to humans and livestock. Aflatoxins have been largely researched to be found in various cereals, oilseeds, spices, and nuts (Reddy et al., 2010).

Certain moulds such as Aspergillus flavus and Aspergillus parasiticus produce aflatoxins which grow in soil, decaying vegetation and grains. They flourish under favourable conditions typically found in tropical and subtropical regions, including high temperature, high humidity and tend to invade foods. Food crops can be contaminated at various steps during harvesting or storage. Fungal contamination can occur in the field, or during harvest, transport and storage.

According to Ehrlich & Cotty (2004) mycotoxins, including aflatoxin, have had adverse impacts on most crops around the globe. Even though the extent of aflatoxin toxicity varies according to the commodities, it can infect crops during growth phases or even after harvesting.

Exposure to this toxin poses serious hazards to human health (Faisal et al., 2008). Commodities such as maize, groundnuts, pistachio, Brazil nuts and coconut are highly prone to contamination by aflatoxin, whereas wheat, oats, millet, barley, rice, cassava, soybeans, beans, pulses, and sorghum are usually resistant to aflatoxin contamination (WHO, 2018).

However, agricultural products such as cocoa beans, linseeds, melon seeds and sunflower seeds are seldom contaminated. Despite several research and control measures, aflatoxin is still a major threat to food and agricultural commodities.

The biocontrol principle of competitive exclusion of toxigenic strains of A. flavus involves the use of non-toxigenic strains to reduce aflatoxin contamination in maize (Cusato et al., 2013). The use of biocontrol agents such as Bacillus subtilis is effective at control and management of aflatoxins. Several strains of B. subtilis are isolated from the non-rhizosphere of maize soil have been reported to eliminate aflatoxin. Several approved products can control aflatoxin build up.

However, Good agricultural practices (GAPs) also help control the toxins to a larger extent, such as timely planting, providing adequate plant nutrition, controlling weeds, and crop rotation, which effectively controls A. flavus infection in the field.

Heeding to the 4R nutrient stewardship (fertilizer from the right source, applied at the right rate, at the right time and in the right place) also helps in reducing fungi build up. Yara International, being the world’s leading crop nutrition company has a range of well-formulated fertilizers with a unique plant biostimulant technology that strengthens crops and reduces adverse fungal activity.

References

Cusato, S., Gameiro, A. H., Corassin, C. H., Sant’ana, A. S., Cruz, A. G., Faria, J. D. A. F., & De Oliveira, C. A. F. (2013). Food safety systems in a small dairy factory: Implementation, major challenges, and assessment of systems’ performances. Foodborne Pathogens and Disease, 10(1), 6–12. https://doi.org/10.1089/fpd.2012.1286

Ehrlich, K. C., & Cotty, P. J. (2004). An isolate of Aspergillus flavus used to reduce aflatoxin contamination in cottonseed has a defective polyketide synthase gene. Applied Microbiology and Biotechnology, 65(4), 473–478. https://doi.org/10.1007/s00253-004-1670-y

Faisal, K., Periasamy, V. S., Sahabudeen, S., Radha, A., Anandhi, R., & Akbarsha, M. A. (2008). Spermatotoxic effect of aflatoxin B1 in rat: Extrusion of outer dense fibres and associated axonemal microtubule doublets of sperm flagellum. Reproduction, 135(3), 303–310. https://doi.org/10.1530/REP-07-0367 Reddy, K. R. N., Salleh, B., Saad, B., Abbas, H. K., Abel, C. A., & Shier, W. T. (2010, March). An overview of mycotoxin contamination in foods and its implications for human health. Toxin Reviews, Vol. 29, pp. 3–26. https://doi.org/10.3109/15569541003598553

Wannop, C. C. (1963). Groundnut Toxicity in Poultry: British Veterinary Journal, 119(4), 174–177. https://doi.org/10.1016/s0007-1935(17)42453-5 WHO. (2018). Food Safety Digest: Aflatoxins.