The fungal disease Fusarium head blight affects cereal grains and can produce mycotoxins, like the water-soluble deoxynivalenol (DON). Wheat wet milling process begins with ground endosperm obtained by dry milling and ends with the separation of starch from gluten. Research was conducted on hard red spring wheat and durum wheat samples naturally contaminated with DON. The fate of DON in wheat dry milled fractionations (farina/semolina, shorts, and bran) during wet milling was investigated. Three wet milling processes were evaluated. DON levels were assessed by GC-ECD. Results showed that DON was present in all dry milled fractions. DON concentration in farina and semolina exceeded the safety threshold for human consumption. After wet milling farina and semolina, nearly all the DON was found in the water-soluble fraction, regardless the wet milling process. A negligible level of DON was found in the gluten extracted from HRSW with Martin wet milling process.

The highly toxic fungal metabolite, neosolaniol monoacetate, was isolated and purified from cultures of Fusarium sambucinum. Since little is known about its toxic properties, the biological effects of this trichothecene were compared to those caused by diacetoxy-scirpenol in male Wistar rats. The lesions caused by the two toxins were very similar. Chronic exposure to either toxin led to a significant decrease (P<0.05) in red blood cell counts and a significant increase (P<0.05) in platelet size. The major pathological lesions observed were atrophy of the actively dividing cells of the bone marrow, thymus, spleen and lymph nodes. The reported species difference in T-2 toxin toxicity was investigated by determining the deacylation rate of T-2 toxin to HT-2 toxin, one of the first steps in the detoxification of this trichothecene. The high deacylation rate catalysed by rat microsomes correlated with the low sensitivity of this species to T-2 toxin, whereas the low deacylation rates with cat and monkey microsomes agreed with their high sensitivity. In contrast to this, the apparently high toxicity of T-2 toxin to humans does not correlate with the high deacylation rate observed in human hepatic microsomes. Involvement of the UDP-glucuronyltransferases in the detoxification of T-2 toxin was studied with rat and pig hepatic microsomes. T-2 toxin and two of its metabolites, HT-2 toxin and T-2 tetraol, did not appear to act as substrates for these enzymes under the in vitro conditions used.

The purpose of the study was to: ° Report on the occurrence of mycotoxins in grain and grain products in South Africa; ° Compare with other countries; ° Weigh the evidence regarding effects on health of test animals, and human and animal consumers; ° Determine the need for statutory measures to regulate mycotoxins in food; and ° Propose practical measures for controlling mycotoxins in grain and grain products in South Afica. Good mycotoxin data for maize were obtained from the author's surveys. Data on other local grains is lacking. In domestic maize, fumonisins and deoxynivalenol occur regularly, at levels as low or lower than in Argentina and the USA. Other mycotoxins occur rarely, or at very low levels. Deoxynivalenol is likely to occur regularly in domestic wheat. Aflatoxins were virtually absent in domestic maize, but often occur at concerning levels in imported Argentinean and USA maize. The literature show that aflatoxins are acutely and chronically toxic to humans and animals and most countries maintain regulatory Maximum Tolerable Levels (MTLs) for aflatoxins in grain and grain products. Several countries also maintain regulatory MTLs for deoxynivalenol, based on lesser scientific evidence. The mycotoxin that occurs most frequently in South African maize, is the fumonisin B group of analogues, with fumonisin B1 the most abundant. Fumonisins are produced by Fusarium verticillioides (previously known as Fusarium moniliforme) and occur in maize worldwide. Fumonisins cause leukoencephalomalacia in horses, pulmonary oedema in pigs, liver cancer in rats and liver and kidney damage in other animals. A statistical relationship between the occurrence of F. verticillioides and fumonisins in maize and oesophageal cancer in humans has been demonstrated in Transkei and in China. The 'toxins derived from F. moniliforme' and fumonisin B1 have been evaluated as Group 2B carcinogens i.e. possibly carcinogenic to humans, by the International Agency for Research on Cancer of the World Health Organisation. Based on a review of epidemiological and toxicological evidence of the effects of fumonisins on humans and animals, their occurrence in maize and maize products, previously proposed MTLs, and the practical implications of MTLs set for maize and maize products, we propose the following MTLs for total fumonisins in maize and maize products for human consumption: ° 4 µg/g in whole, uncleaned maize; ° 2 µg/g in dry-milled maize products with fat content of >3.0 %, dry weight basis (e.g., sifted and unsifted maize meal); and ° 1 µg/g in dry-milled maize products with fat content of <3.0 %, dry weight basis (e.g., flaking grits, brewers grits, samp, maize rice, super and special maize meal) These MTLs are too high to address a possible link of fumonisins with neural tube defects in neonates. This potential problem remains to be addressed, possibly by fortification of maize products with folic acid. We propose MTLs for deoxynivalenol of 2 µg/g in cereal grains for food use, and 1 µg/g in cereal grain food products. Finally, we propose that the current regulatory MTLs for aflatoxins be raised from 10 ng/g (total aflatoxins in unprocessed maize) to 20 ng/g. / Dissertation (PhD)--University of Pretoria, 2003. / Microbiology and Plant Pathology / Unrestricted

The necessity to obtain accurate and reliable data pertaining to the range and/or levels of mycotoxin contamination in a variety of food and feed substrates, intended for human or animal consumption, has therefore, become important. An integral part of this study will be the provision of the most suitable analytical methods for the determination of selected Fusarium mycotoxins, in maize. The culmination will be the application of those selected methodologies to a series of Transkeian maize samples associated with human oesophageal cancer-risk.

Philosophiae Doctor - PhD / Mycotoxins attract worldwide attention because of the significant economic losses associated with their impact on human health, animal productivity, domestic and international trade. Over 300 mycotoxins have been discovered, of which a few are of serious concern (Smith and Moss 1985; Rheeder et al., 1994). Exposure to these mycotoxins can produce both acute and chronic effects ranging from death to effects upon the central nervous, cardiovascular, pulmonary systems and upon the alimentary tract. Mycotoxins may be carcinogenic, mutagenic, teratogenic and immunosuppressive (Ferrante et al., 2002). Mycotoxins are currently considered as a major problem in developing countries (Miller, 1994).

No description available.

No description available.

M.Tech. / A study to determine the occurrence of fungi and their mycotoxins in rural food and their effect on human health was carried out at N’wamitwa (Tzaneen), a rural area of Limpopo province (South Africa). Fifty-eight maize and twenty-nine bambara nuts samples were collected from selected house holds and taken to the storage facilities of the Food, Environment and Health research group (FEHRG) laboratory at the University of Johannesburg for analysis. The samples were analysed for moisture content, fungal infestation, mycotoxin contamination and their toxicity. The moisture content of the samples were at a range of 3-20% moisture. Fungi which included species of the genus Aspergillus, Fusarium and Penicillium were detected at all moisture ranges but more dominant in samples with higher moisture levels. Fungi in this study were able to produce mycotoxins which included deoxynivalenol (DON), zearelenone (ZEA), aflatoxins (AFs), T2- toxin, fumonisins (FBs), ochratoxin A (OTA) and citrinin. The most dominant toxins in maize samples quantified by VICAM were AFs followed by DON, FBs and lastly ZEA and in bambara nuts were FBs followed by DON, AFs and ZEA. HPLC was able to detect higher concentrations of FBs than VICAM. The toxins were then tested for their toxicity using human lymphocytes and the most toxic was DON followed by AFs, FBs and lastly ZEA. Three vials of the same toxin with different concentrations, one with the highest and others with the middle and the lowest concentrations were used to treat the human lymphocytes.

M. Tech.

Mycotoxins are secondary metabolites of fungi, which may contaminate animal feed and human food at all stages of the food chain. This has become a global concern and considered an important risk factor mostly for human and animal health. The aim of this project was to elucidate the general health and productivity of domesticated animals in selected rural areas of the Limpopo Province in relation to fungi and mycotoxin and find out possible solutions to avoid in the future further exposure and to improve animal production in rural areas. A total of 95 animal fresh faeces (50 from Mapate and 45 from Nwanedi districts), 50 feed samples (24 from Mapate and 26 from Nwanedi) and 50 fresh milk samples from cattle and goats were screened for fungi and mycotoxin contamination. The multi mycotoxin extraction method was used, followed by thin layer chromatography, also the VICAM immunoaffinity clean up, high performance liquid chromatography, gas chromatography mass spectrophotometry and the ELIZA enzyme linked kit method were used for further mycotoxin determination and quantification. The results obtained from this study revealed that species of Aspergillus, Fusarium and Penicillium fungi contaminated both feed and animal faeces samples. The species Aspergillus niger, A. clavatus, A. flavus, A. fumigatus, Fusarium verticillioides, F. graminerium and F. proliferatum were the most prevalent fungi. Fumonisin B1 and B2, aflatoxins B1, zearalenone and deoxynivalenol (DON) were found in animal feed. Fumonisins B1 and B2 were also found in faecal samples which indicated animal exposure to these mycotoxins. Cattle were the most exposed as compared to goats and pigs. In addition, aflatoxin M1 and traces of fumonisin B1 was detected in cattle and goats milk samples collected from both Mapate and Nwanedi districts. Late harvesting and poor handling of crops during storage seemed to be the reason for the results indicating feed contamination with high levels of fungi and mycotoxins. Daily exposure to this contaminants may influence or/and induce several symptoms such as dermatosis, immunosupression, liver and oesophageal cancer in both animal and human being. There is an urgent necessity to teach rural populations simple and cheap methods of crops storage and techniques to prevent feed and food contamination. / Prof. Mike F. Dutton Mr. F. Eric Van-Zyl