Determination of pesticide residues in rooibos (Aspalathus linearis) teas in South Africa.

An efficient gas chromatography-mass spectrometry approach was used in this study to quantify 13 pesticide residues in rooibos teas purchased from registered retail outlets in South Africa between November 2019 and April 2020. A QuEChERS (Quick, easy, cheap, effective, rugged, and safe) procedure was used to extract pesticides using 7.5 mg of graphitized carbon black (GCB), 50 mg of primary secondary amine (PSA), and 150 mg of anhydrous MgSO4. In order to compensate for the matrix effect, matrix matched calibration curves ranging from 10 µg/kg-500 µg/kg were applied for accurate quantification. For validation purposes, accuracy tests were conducted using a blank tea sample spiked with pesticide standards at two different concentrations (10 and 100 µg/kg). Most of the analytes were recovered within acceptable recovery ranges (72-106%), with a relative standard deviation of less than 20%. The limits of quantification were low, all falling below 10 µg/kg which meets the maximum residue limits (MRLs). The validated method was used to analyze 100 tea samples, and among the pesticides analyzed, deltamethrin and lambda-cyhalothrin were detected in only one samples at a concentration (92.11 and 66.41 µg/kg, respectively) below the MRLs stipulated by the European Union. The level of pesticides that are commonly used in tea should be checked often.

Review on microbial degradation of aflatoxins.

Aflatoxin (AF) contamination presents one of the most insidious challenges to combat, in food safety. Its adulteration of agricultural commodities presents an important safety concern as evident in the incidences of its health implication and economic losses reported widely. Due to the overarching challenges presented by the contamination of AFs in foods and feeds, there is an urgent need to evolve cost-effective and competent strategies to combat this menace. In our review, we tried to appraise the cost-effective methods for decontamination of AFs. We identified the missing links in adopting microbial degradation as a palliative to decontamination of AFs and its commercialization in food and feed industries. Cogent areas of further research were also highlighted in the review paper.

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.

Mycotoxic nephropathy in Bulgarian pigs and chickens: complex aetiology and similarity to Balkan endemic nephropathy.

Spontaneous nephropathy in Bulgaria, which is observed frequently during meat inspection and which differs morphologically from the classical description of mycotoxic porcine/chicken nephropathy as made in Denmark, was found to have a multi-mycotoxic aetiology being mainly provoked by a combined effect of ochratoxin A, penicillic acid and fumonisin B1 in addition to a not-yet-known metabolite. Mean contamination levels of ochratoxin A were consecutively low (188.8 and 376.4 microg kg(-1)) in contrast to high contamination levels of fumonisin B1 (5564.1 and 3254.5 microg kg(-1)) and penicillic acid (838.6 and 904.9 microg kg(-1)) for 2006 and 2007, respectively. Some other mycotoxins with lower importance such as citrinin, penitrem A, etc., may also influence clinicopathological picture of this nephropathy. A heavy contamination with Gibberella fujikuroi var. moniliformis (Fusarium verticillioides) and Penicillium aurantiogriseum complex (mainly Penicillium polonicum) was observed in almost all examined feed samples coming from pig and chick farms with nephropathy problems from Bulgaria. In contrast, low contamination with Aspergillus ochraceus, Penicillium verrucosum and Penicillium citrinum was observed in the same feed samples and these species were isolated as very rare components of the mycobiota.