Fumonisin mycotoxins in traditional Xhosa maize beer in SA
Gordon S. Shephard,* Liana vd Westhuizen, Pumza M. Gatyeni, Nontuthuzelo I.M. Somdyala, Hester-Mari Burger and Walter F.O. Marasas
Promec Unit, Medical Research Council, PO Box 19070, Tygerberg 7505, SA

Summary
The fumonisin mycotoxins, mainly produced on maize by the fungus Fusarium verticillioides, occur widely in maize and maize-based products. They have been classified by the International Agency for Research on Cancer (IARC) as possible human carcinogens. The production and consumption of home-brewed Xhosa maize beer is a widespread traditional practice in the former Transkei region of South Africa. Data on the consumption of home-brewed maize beer are not available, but on the basis of published data for the consumption of commercial beer in South Africa, the exposure to fumonisin mycotoxins in these districts among the consumers of maize beer was found to be well above the provisional maximum tolerable daily intake as set by the Joint FAO/WHO Expert Committee on Food Additives (JECFA).

The aim of this study was to determine the fumonisin mycotoxin levels in samples of home-brewed maize-based beers prepared by the Xhosa-speaking population in the former Transkei region of the Eastern Cape Province of SA and to estimate the extent to which this could contribute to fumonisin exposure of this population.

Samples of home-brewed maize-based beer (known as mqomboti in isiXhosa) were obtained prior to various local “drinking parties” in the Centane and Bizana magisterial districts of former Transkei between 2001 and 2004.

The origin of the fumonisin mycotoxins in these beers was presumed to be fumonisin-contaminated maize. The home brewing of maize-based beer is widely practiced and enjoyed in rural subsistence farming areas of South Africa. Mouldy home-grown maize, specifically separated from good (visibly non-mouldy) maize by the householders after harvest, is frequently used as a component, and it is said to impart a desirable taste to the final beer product.

Conclusion
The range of levels in maize beer observed in both districts was large, and statistical analysis revealed that these differences were not significant. It is universal custom in these areas to hand-sort each maize harvest into good (visibly non-mouldy) and mouldy maize cobs, a practice that is expected to reduce fumonisin exposure. However, the use of the mouldy maize for beer-brewing obviates the food safety benefit derived from the original separation.

The results of this research indicated that the consumption of maize beer in rural areas of former Transkei can significantly enhance fumonisin exposure and that, among beer consumers, the provisional maximum tolerable daily intake (PMTDI) set by JECFA can easily be exceeded. The situation is exacerbated by the high prevalence of the use of mouldy maize as an ingredient of choice and can be addressed only by education and a change in lifestyle.