Contamination with storage fungi of human food from Cameroon

Food, Environment and Health Research Group, Faculty of Health Science, 2028, University of Johannesburg, Doornfontein Campus, 2028 Gauteng, South Africa.
International journal of food microbiology (Impact Factor: 3.08). 09/2009; 135(3):193-8. DOI: 10.1016/j.ijfoodmicro.2009.08.001
Source: PubMed


In a mycological study, a total of 95 human food samples were investigated to evaluate the incidence of fungal contamination in Cameroon by conventional identification method and partly confirmed by DNA sequencing. The isolated fungal spp. were further studied to determine their toxigenic potentials. The investigation revealed the predominance of Aspergillus and Penicillium with 96% of samples contaminated with at least one species of these fungi, whereas the incidence of co-contamination of samples was 85%. Aspergillus flavus and Aspergillus parasiticus (Flavi section) were the most predominant species contaminating mainly maize and peanuts. In addition, P. crustosum and P. polonicum were the most common contaminants belonging to the genus Penicillium. On the other hand, A. ochraceus (Circumdati section) registered a low incidence rate of 5%, including other members of the Aspergillus group. Other members of the genera Rhizopus and Alternaria spp. were also registered in the study. A majority of fungal strains of A. ochraceus, A. parasiticus, P. crustosum and P. polonicum isolated were toxigenic, producing the mycotoxins tested for, while none was detected in cultures of A. fumigatus. The high incidence rate of fungi contamination coupled with their potentials in producing mycotoxins gives a strong indication that the samples tested may likely be contaminated with various mycotoxins. There is need for further study to assess the incidence of mycotoxins contamination in similar food samples.

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    • "A quarter of the world's food crops are estimated to be affected by mycotoxins; creating a large economical loss in the developed and developing countries (Kumar and Rajendran, 2008). Other reports indicate even higher contamination rate of aflatoxin (Njobeh et al., 2009). Exposure to higher levels of aflatoxin contamination increases cancer incidence, including risk of hepato-cellular carcinoma especially in 6-to 9-year-old girls and neural tube defects (Umoh et al., 2011). "
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    ABSTRACT: Aflatoxins are secondary fungal metabolites that contaminate agricultural commodities and can cause sickness or death in humans and animals. Risk of aflatoxin contamination of food and feed in Africa is increased due to environmental, agronomic and socioeconomic factors. Temperature, food substrate, strain of the mould and other environmental factors are some parameters that effect mycotoxin production. Preventing mycotoxin production at farm level is the best way to control mycotoxin contamination. Advances in molecular techniques and other decontamination methods such as gamma-irradiation and microwave heating could help to deal with these issues. Mycotoxins could be used as an energy source for a group of aerobic microorganisms, which are suitable to mycotoxin biodegradation. Several protocols have been provided to biodegrade mycotoxins in food and feed using potential bacteria such as Lactobacillus and Bifidobacterium. However, there are varieties of responses between different microorganisms against mycotoxins. For example, Bacillus brevis were not affected by high concentrations of trichothecene. Application of microorganisms needs to be evaluated from a safety point of view. Application of microorganisms on mycotoxin degradation, food and feed materials also need to be investigated. Further studies need to be conducted to address the seasonal variation of aflatoxin contamination in food and feed. Understanding the seasonal variation could help demonstrate and develop more effective decontamination methods. For example, it is postulated that mycotoxin issues due to monsoons in Hungary could possibly be concluded to technical difficulties in pre-and post-harvest operations. Application of advanced methods such as DNA biosensors and infrared spectroscopy for rapid and accurate detection of mycotoxin and related fungi is increasing dramatically. Application of new and advanced detection techniques could enable the agricultural industry to deal more effectively with the occurrence of aflatoxin contamination.
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    • "Injection volume per analyte or standard concentrations (5 µg/mL, 10 µg/mL and 20 µg/mL) was 20 µL. OTA analysis was performed by the fluorescent detection method (Abdulkadar et al. 2004; Njobeh et al. 2009) with some modifications. The mobile phase consisting of 2% acetic acid/acetonitrile (49:51, v/v) was pumped at a flow rate of 0.8 mL/min. "
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    ABSTRACT: This study analysed 60 dog food samples obtained from commercial outlets following the 2011 aflatoxicosis outbreak in South Africa. Results obtained from the selected dog food samples revealed that 87% of samples were contaminated with aflatoxins (AFs) (mainly AFB1 and AFB2). Amongst these samples, 45 (75%) were above the 20 parts per billion (ppb) set by most countries and 10 ppb regulated by the Fertilizers, Farm Feeds, Agricultural Remedies and Stock Remedies Act (Act No. 36 of 1947) for South Africa. In addition to AFs, other mycotoxins were also detected in the same samples with fumonisins (FBs) (mainly FB1 and FB2) contaminating 98% of samples with 49 (81.81) above the tolerable limit of 1000 ppb in feedstuff set up by the Federal Drug Agency (FDA) (USA). The FBs mean obtained was 1556 ppb (Table 1) with contamination varying between 5.2 and 4653.8 ppb. Ochratoxin A (OTA) was detected in 41 (68%) of the analysed samples, with a mean value of 13.7 ppb. Amongst these samples, 15 (25%) were above the 20 ppb highest limit set by the Codex Alimentarius standard. Zearalenone (ZEA) was detected in 96% of samples, with a mean value of 354.1 ppb. Thirty-three samples (55%) were above the regulated level 1000 ppb tolerable limit. The recoveries were up to ten times the tolerable daily limits of the FDA and EU. The correlation between mycotoxin findings and clinical signs reported on patients presented for aflatoxicosis led to the conclusion that the outbreak was associated with the presence of other mycotoxins found simultaneously in the analysed samples by additive or synergistic effects.
    02/2013; 84(1):E1-5. DOI:10.4102/jsava.v84i1.133
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    • "Tel: +98-918-3806512. conducive to fungal growth and toxin production (Njobeh et al., 2009; Bhattacharya and Raha, 2002; Bankole et al., 2005; Abdel-Gawad and Zohri, 1993). The storage temperature, moisture content, presence of oxygen and gaseous composition are the most important factors influencing the development of fungi during storage in these nut seeds (Ayyasam and Baskaran, 2005). "
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    ABSTRACT: Aspergillus flavus produces secondary metabolites called aflatoxin that has powerful teratogenic, mutagenic and hepato-carcinogenic effects. The aim of this study was to evaluate the A. flavus of pistachio and peanuts from Sanandaj, Iran. Pistachio and peanut nuts samples were obtained from dried fruit retail shops of Sanandaj, 2011. One hundred grams from each sample were sterilized in a 0.4% sodium hypochlorite solution for 2 min. Subsequently, the sample was rinsed once in distilled water and allowed to dry. Each sample was grounded into powder by vortex and then 1 g was poured into 100 ml of sterile distilled water and stirred. Next, 1 ml of the supernatant was inoculated into Petri dishes containing Sabouraud dextrose agar then incubated at 25°C for five days. The grown fungi were identified by standard mycological techniques based macroscopic and microscopic morphology. Of the 132 samples (peanut: n = 81; pistachio: n = 51), fungi were detected in almost 72% of the samples. The A. flavus was the most predominant isolate from peanut (19%) and pistachio (22%) samples. There was a significant relationship between A. flavus contaminations in the peanuts and pistachio with high humidity. Therefore, due to the isolation of high percentage of A. flavus as the main aflatoxins producer in nature, we recommended the need for good storage practices in order to prevent the occurrence of aflatoxins in peanuts and pistachio.
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