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Burger H.-M.,Programme on Mycotoxins and Experimental Carcinogenesis PROMEC Unit | Burger H.-M.,Stellenbosch University | Shephard G.S.,Programme on Mycotoxins and Experimental Carcinogenesis PROMEC Unit | Louw W.,Southern African Grain Laboratory | And 3 more authors.
International Journal of Food Microbiology | Year: 2013

Mycotoxin contamination of maize and maize-based food and feed products poses a health risk to humans and animals if not adequately controlled and managed. The current study investigates the effect of dry milling on the reduction of fumonisins (FB), deoxynivalenol (DON) and zearalenone (ZEA) in maize. Five composite samples, constructed to represent different mycotoxin contamination levels were degermed yielding degermed maize and the germ. The degermed maize was milled under laboratory conditions and four major milling fractions (SPECIAL, SUPER, semolina (SEM) and milling hominy feed) collected. The whole maize, degermed maize and total hominy feed (germ. +. milling hominy feed) were reconstructed to ensure homogenous samples for mycotoxin analyses. For comparison, commercial dry milling fractions (whole maize, SPECIAL, SUPER and total hominy feed), collected from three South African industrial mills, were analysed for the same mycotoxins and hence a more accurate assessment of the distribution between the different milling fractions. The distribution of the mycotoxins during the experimental dry milling of the degermed maize differs, with FB mainly concentrated in the SPECIAL, DON in the SEM whereas ZEA was equally distributed between the two milling fractions. Distribution of mycotoxins between the fractions obtained during commercial dry milling generally provided similar results with the total hominy feed containing the highest and the SUPER milling fractions the lowest mycotoxin levels although variations existed. Although milling is an effective way to reduce mycotoxins in maize, kernel characteristics and resultant fungal colonisation may impact on the distribution of specific mycotoxins among the different milling fractions. Differences in industrial dry milling practices and problems encountered in sampling bulk maize remain a large problem in assessing mycotoxin contamination in milling fractions intended for human consumption. © 2013 Elsevier B.V.

Thembo K.M.,University of Limpopo | Thembo K.M.,Programme on Mycotoxins and Experimental Carcinogenesis PROMEC Unit | Vismer H.F.,Programme on Mycotoxins and Experimental Carcinogenesis PROMEC Unit | Nyazema N.Z.,University of Limpopo | And 3 more authors.
Journal of Applied Microbiology | Year: 2010

Aims: To investigate the antifungal activity of aqueous and organic extracts of four weedy plant species viz. Tagetes minuta, Lippia javanica, Amaranthus spinosus and Vigna unguiculata against isolates of four agriculturally important fungi, i.e. Fusarium verticillioides, F. proliferatum, Aspergillus flavus and A. parasiticus. Methods and Results: Dried powdered aerial parts of the plants were extracted sequentially with hexane, dichloromethane, methanol and water and tested for activity using a serial microdilution assay. Results were read every day over 120 h. All extracts except for the water extracts showed growth inhibitory activity against most isolates of the Fusarium spp. The most active were the methanol and hexane extracts of V. unguiculata and A. spinosus with minimum inhibitory concentration (MIC) values of <0·5 mg ml-1 after 48 h against Fusarium spp. No inhibition of the Aspergillus spp. tested was observed, but conidium formation was stimulated on plates treated with plant extracts when visually compared to the growth controls. Conclusions: The results obtained from this study indicated that chemical constituents from these plant species may be developed as potential agrochemical fungicides. Significance and Impact of the Research: Food and feed are subject to infection by a variety of micro-organisms that can induce spoilage andor produce metabolites that are toxic to humans and animals. Extracts of V. unguiculata and A. spinosus were most active and maybe developed into environmentally friendly fungicides, which are affordable to rural farmers in developing countries. © 2010 The Society for Applied Microbiology.

Burger H.-M.,Programme on Mycotoxins and Experimental Carcinogenesis PROMEC Unit | Burger H.-M.,Stellenbosch University | Lombard M.J.,Stellenbosch University | Shephard G.S.,Programme on Mycotoxins and Experimental Carcinogenesis PROMEC Unit | And 4 more authors.
Food and Chemical Toxicology | Year: 2010

A validated culturally specific dietary assessment method was used to determine the habitual maize intakes of black Xhosa-speaking Africans living in the Centane region of the Eastern Cape Province to assess their exposure to the carcinogenic fumonisin mycotoxins. The mean total dry weight maize intakes of home-grown, commercial or combined (both maize sources) were 474, 344, 462gday-1, respectively. When considering the total mean levels of fumonisin in home-grown maize (1142μgkg-1) and commercial maize (222μgkg-1), the probable daily intakes (PDI's), expressed as μgkg-1 body weight day-1 were 12.1 (95%CI: 0.3-4926.5) and 1.3 (95%CI: 1.0-1.8) for men and 6.7 (95%CI: 1.0-457.8) and 1.1 (95%CI: 0.9-1.3) for women, consuming home-grown and commercial maize, respectively. Based on the different maize-based beer drinking frequencies the PDI's varied between 6.9 and 12.0μgkg-1/drinking event. Depending on the maize intake patterns an exposure " window" exists where fumonisin exposure is below the recommended group provisional maximum tolerable daily intake (PMTDI) for fumonisins of 2μgkg-1bwday-1. The assessment of fumonisin exposure and development of preventative strategies depend, not only the accurate determination of total fumonisin levels in maize, but also on the distinct dietary patterns of a specific population. © 2010 Elsevier Ltd.

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