PubMed · 15811817
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Mary Eubanks. 2005. MIT toxicogenomics research program.. https://doi.org/10.1289/ehp.113-a234
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Aflatoxin (AF) contamination poses a severe global threat to food and medicinal material safety, yet existing research focuses on terminal AF metabolites while neglecting residual biosynthetic precursors, leading to potential underestimation of contamination risks. In this study, a UPLC-MS/MS method was established for the simultaneous quantification of six AFs and their five precursors in lotus seeds, with optimization of mass spectrum parameters, chromatographic separation conditions, and sample pretreatment. Method validation confirmed linearity (R2 > 0.99), LODs (0.03-0.36 μg/kg), and recoveries (76.53%-120.0%, RSD < 15%). Analysis of 41 natural lotus seed samples revealed a 63.4% AF contamination rate, dominated by B-group AFs, while O-methylsterigmatocystin (OMST) and versicolorin hemiacetal (VOH) were identified as the primary co-residual precursors with co-occurrence rates ≥ 50%. Notably, AFM1 was predominantly detected in natural samples with AFB1 concentrations exceeding 100 μg/kg. Artificial inoculation experiments further demonstrated that sterilization and sealing conditions modulated AF biosynthesis in lotus seeds, with non-sterilized and non-sealed groups showing delayed fungal metabolism and lower toxin accumulation. A significant linear correlation was observed between AFM1 and AFB1 levels (r = 0.94) in infected samples, demonstrating their accumulation levels are coupled with fungal overall metabolic flux. Given the high co-occurrence rate of OMST/VOH with AFB1 in natural samples, their individual and combined toxicities require in-depth investigation. This work deciphers matrix-specific AF dynamics in lotus seeds, supporting regulatory standard refinement (e.g., precursor inclusion) and targeted control (e.g., time-sensitive drying after harvest). Further studies will focus on exploring the molecular mechanisms of substrate-dependent AF synthesis.
The aim of this study was to investigate the distribution of aflatoxins and zearalenone levels in various corn-milling fractions. Corn kernels and six derived milling fractions (germ, bran, large and small grits, flour, and animal feed flour) were sampled in an industrial plant; both conventional and organic corns were sampled. To evaluate the effect of cooking, samples of polenta were prepared starting from naturally contaminated flour. Conventional and organic lots showed mycotoxin contamination. For both lots, germ, bran, and animal feed flour showed a marked concentration factor from 239 to 911% accounting for both the low yields of the derived products and the distribution of aflatoxins and zearalenone contamination in the outer parts of the kernels. Conversely, a reduction factor of at least four times from raw material to finished products was observed. Polenta samples were unaffected by the cooking process, with levels of contamination similar to those of starting flour.
A study to determine mould incidence and aflatoxin contamination of maize kernels was carried out among dealers (traders) in the three agroecological zones of Uganda. The maize kernels were categorized into those stored for two to six months or for more than six months to one year. Results indicate that the mean moisture content of the kernels was within the recommended safe storage levels of < or =15% but was significantly lower in the Highland maize kernels followed by the Mid-Altitude (dry) kernels while the Mid-Altitude (moist) kernels had the highest levels. Across the agroecological zones, Aspergillus, Fusarium, Penicillium and Rhizopus were the most predominant fungal genera identified and, among their species, A. niger had the highest incidence, followed by A. flavus, F. verticillioides, A. wentii, A. penicillioides and Rhizopus stolonifer. There were more aflatoxin positive samples from the Mid-Altitude (moist) zone (88%) followed by those samples from the Mid-Altitude (dry) zone (78%) while samples from the Highland zone (69%) were least contaminated. Aflatoxin levels increased with storage time such that maize samples from the Mid-Altitude (dry and moist) stored for more than six months had mean levels greater than the 20 ppb FDA/WHO regulatory limits. Aflatoxin B1 was the most predominant type and was found to contaminate maize kernels from all the three agroecological zones. These results indicate that maize consumers in Uganda are exposed to the danger of aflatoxin poisoning. Thus, there is the need for policy makers to establish and enforce maize quality standards and regulations related to moulds and aflatoxins across the agroecological zones to minimize health hazards related to consumption of contaminated kernels.