Judith Zanele Phoku

Fusarium infection of maize and maize-based products and exposure of a rural population to fumonisin B1 in Limpopo Province, South Africa

Fusarium species (spp.) and fumonisin B1 (FB1) contaminations were monitored in maize and porridge consumed by a rural population of Limpopo Province, South Africa. Faecal samples were also analysed for FB1 as a means of estimating the degree of dietary exposure to this mycotoxin. In total, 142 samples of maize (n = 54), porridge (47) and faeces (41) were screened for Fusarium spp. using a serial dilution technique followed by DNA sequencing, while FB1 was further screened and quantified by thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC), respectively. At least four species of Fusarium were identified, of which F. verticillioides was the most prevalent in all three sample types analysed. The contamination levels of FB1 were significantly higher in 87% of maize sampled (range = 101–53,863 µg kg−1) as compared with porridge (74% incidence rate; range = 0.2–20 µg kg−1) and faecal samples (100% incidence rate; range = 0.3–464 µg kg−1). Thus, it can be deduced that the level of human exposure to FB1 via the consumption of maize was high as several samples contained levels exceeding 1000 µg kg−1, which was strongly supported by the levels found in faecal samples. Further data revealed that a high proportion of FB1 is destroyed or removed by processing maize into porridge. As maize porridge is consumed as a staple, the low levels found provide a means to limit exposure to FB1. Levels of FB1 found in the faeces which were higher indicate that other foods contaminated with the toxin are also consumed.

Co-contamination of Nigerian Cocoa and Cocoa-Based Powder Beverages Destined for Human Consumption by Mycotoxins

Abstract A total of sixty-four (64) samples consisting of cocoa (processed and non-processed) and cocoa based powder beverages were collected from fields, stores and markets in different areas in south-western Nigeria and screened for the five major mycotoxins-aflatoxins (AFs), ochratoxin A (OTA), zearalenone (ZEA), deoxynivalenol (DON) and fumonisins (FBs). Mycotoxins analyses were done after extraction by high performance liquid chromatography (HPLC), which showed contamination of the food commodities by major mycotoxins (AFs, OTA, DON, ZEA and FBs) at different incidences and concentration ranges. Results from HPLC analysis showed concentration of AFs, OTA, fumonisin B1 (FB1), fumonisin B2 (FB2), ZEA and DON up to 16.01μg/kg, 884.8μg/kg, 440μg/kg, 20.2μg/kg, 2364.7μg/kg and 8.5μg/kg respectively in the different food samples analysed. The contamination and co-contamination of these food commodities by some of these mycotoxins at concentrations above the different set regulatory limits by the EU and other countries is of concern with attendant health risks, particularly for Nigerians who consume these contaminated cocoa and cocoa products as part of their diets.

Use of a bio-wipe kit to detect fumonisin B1 in faecal materials

Fusarium toxins with reference to fumonisin B1 (FB1) have long been regarded as contaminants of maize and maize-based related products. However, when consumed they can cause intoxication, especially in humans. Therefore, effective quantitative methods for assessing the dietary exposure of this toxic fungal metabolite are required. The objective of this investigation was to evaluate the effect on the use of a bio-wipe kit, which is a faecal material collection kit, to detect the presence of FB1. Faecal materials were collected from a rural farming community in Gauteng Province, South Africa. In total, 200 samples of faecal material were analysed for Fusarium species using a serial dilution method, while FB1 was further analysed and quantified by reversed-phase TLC and HPLC. The study showed the presence of 11 different Fusarium species grown on potato dextrose agar culture medium of which F. verticillioides and F. proliferatum, producers of FB1, and F. oxysporum were the dominant species. Fumonisin B1 was recorded at an incidence rate of 65% of the total using TLC. Results from HPLC showed that 84% were positive at different ranges of concentration for FB1. This study supports the use of a bio-wipe as a rapid method to determine human exposure to FB1.