Natural occurrence of ochratoxin A in Tunisian cereals

Mycotoxin contamination in the Arab world: Highlighting the main knowledge gaps and the current legislation

Since the discovery of aflatoxins in the 1960s, knowledge in the mycotoxin research field has increased dramatically. Hundreds of review articles have been published summarizing many different aspects, including mycotoxin contamination per country or region. However, mycotoxin contamination in the Arab world, which includes 22 countries in Africa and Asia, has not yet been specifically reviewed. To this end, the contamination of mycotoxins in the Arab world was reviewed not only to profile the pervasiveness of the problem in this region but also to identify the main knowledge gaps imperiling the safety of food and feed in the future. To the best of our knowledge, 306 (non-)indexed publications in English, Arabic, or French were published from 1977 to 2021, focusing on the natural occurrence of mycotoxins in matrices of 14 different categories. Characteristic factors (e.g., detected mycotoxins, concentrations, and detection methods) were extracted, processed, and visualized. The main results are summarized as follows: (i) research on mycotoxin contamination has increased over the years. However, the accumulated data on their occurrences are scarce to non-existent in some countries; (ii) the state-of-the-art technologies on mycotoxin detection are not broadly implemented neither are contemporary multi-mycotoxin detection strategies, thus showing a need for capacity-building initiatives; and (iii) mycotoxin profiles differ among food and feed categories, as well as between human biofluids. Furthermore, the present work highlights contemporary legislation in the Arab countries and provides future perspectives to mitigate mycotoxins, enhance food and feed safety, and protect the consumer public. Concluding, research initiatives to boost mycotoxin research among Arab countries are strongly recommended.

Mycotoxins in Rice Correlate with Other Contaminants? A Pilot Study of the Portuguese Scenario and Human Risk Assessment

Rice is the second most important cereal crop and is vital for the diet of billions of people. However, its consumption can increase human exposure to chemical contaminants, namely mycotoxins and metalloids. Our goal was to evaluate the occurrence and human exposure of aflatoxin B1 (AFB1), ochratoxin A (OTA), zearalenone (ZEN), and inorganic arsenic (InAs) in 36 rice samples produced and commercialized in Portugal and evaluate their correlation. The analysis of mycotoxins involved ELISA, with limits of detection (LODs) of 0.8, 1 and 1.75 μg kg^-1 for OTA, AFB1, and ZEN, respectively. InAs analysis was carried out by inductively coupled plasma mass spectrometry (ICP-MS; LOD = 3.3 μg kg^-1). No sample showed contamination by OTA. AFB1 was present in 2 (4.8%) samples (1.96 and 2.20 μg kg^-1), doubling the European maximum permitted level (MPL). Concerning ZEN, 88.89% of the rice samples presented levels above the LOD up to 14.25 µg kg^-1 (average of 2.75 µg kg^-1). Regarding InAs, every sample presented concentration values above the LOD up to 100.0 µg kg^-1 (average of 35.3 µg kg^-1), although none surpassed the MPL (200 µg kg^-1). No correlation was observed between mycotoxins and InAs contamination. As for human exposure, only AFB1 surpassed the provisional maximum tolerable daily intake. Children were recognized as the most susceptible group.

Mycotoxins occurrence in milk and cereals in North African countries - a review

North African countries; Algeria, Egypt, Libya, Morocco and Tunisia suffer from mycotoxin contamination. Various studies have indicated the presence of mycotoxins in raw milk and cereals (i.e. wheat, barley, maize and cereal-based products). Aflatoxins (AFs), Aflatoxin M1 (AFM1), Ochratoxin A (OTA), Fumonisin (FB1) and Zearalenone (ZEN)-mycotoxin are the most detected due to climatic change in the region. In this review, we will present the kind of foods and feeds cereals and milk based products contaminated and the level of their contaminated mycotoxin. On the other hand, researchers try to find biologic methods to remove/mitigate mycotoxins in food and feed using bio-products. But the research works concerning legislations and mycotoxin risk assessment still rare. Therefore, it appears necessary to make review on the current status of mycotoxins in North African countries in order to explore data related to contamination of basic food in this region and to highlight the problem to the policy-makers to establish a serious legislation on this matter. On the other hand, to give more information to the worldwide readers about the impact of climate change on the food and feed pollution on mycotoxins in the Mediterranean Sea region.

Investigation of ochratoxin a in blood sausages in the Czech Republic: Comparison with data over Europe

Blood sausages consisting of groats, pork, porcine offal, fat, blood, and spices are very popular in the Czech Republic. All these ingredients are potential sources of dietary exposure to ochratoxin A (OTA). OTA has a strong affinity to serum proteins in porcine blood. Thus, the contamination of blood sausages with OTA can be expected. This study aims to evaluate OTA in 200 samples of porcine blood sausages purchased at the Czech market during 2020-2021. The analytical method high-performance liquid chromatography coupled with fluorescence detection with pre-treatment using immunoaffinity columns was employed to determine OTA. The limit of detection was 0.03 ng/g and the limit of quantification 0.10 ng/g. Recovery was 71.6 %. All samples were positive at contents ranging from 0.15 to 5.68 ng/g with a mean of 1.47 ng/g, and a median of 1.26 ng/g. A total of 66% of these samples contained OTA content exceeding the maximum limit of 1 ng/g set in Italy. This study demonstrates that the Czech population is exposed to OTA from blood sausages. The proposed preliminary action limit for OTA in blood sausages should be set at 1 ng/g. No regulatory limits for OTA in blood sausages have been established yet in the European Union legislation. To protect human health, further monitoring of OTA in these products is necessary.

Natural Co-Occurrence of Multiple Mycotoxins in Unprocessed Oats Grown in Ireland with Various Production Systems

The natural co-occurrence of 42 mycotoxins was investigated in unprocessed oat grains grown in Ireland. The sample set included a total of 208 oat crops harvested during 2015–2016 and produced using conventional, organic, or gluten free farming systems. A range of different toxins was identified, including the major type A (neosolaniol, HT-2 and T-2 toxins, T-2 triol, and T-2-glucoside, co-occurring in 21 samples) and B trichothecenes (deoxynivalenol, nivalenol, and deoxynivalenol-3-glucoside), enniatins (B1, B, and A1, co-occurring in 12 samples), as well as beauvericin, alternariol, mycophenolic acid, and sterigmatocystin. The influences of sowing season, year, and production system were investigated, eventually indicating that the latter factor may have a higher impact than others on the production of certain mycotoxins in oats. The most frequently quantified compounds were HT-2 (51%) and T-2 (41%) toxins, with gluten free oats containing significantly lower concentrations of HT-2 compared to conventionally produced oats. Although the prevalence and concentrations of mycotoxin found in oat samples in this study should be substantially reduced by processing. However, as mycotoxin occurrence is clearly influenced by multiple factors, controlled field trials should be carried out to define optimal agronomic practices and mitigate mycotoxin production. Furthermore, this work highlights the need for regularly testing cereal-based foods with multi-residue analytical methods with wider specificities than the traditionally screened and regulated toxins, to generate knowledge on the occurrence of several mycotoxins that are, to date, rarely investigated.

Incidence and exposure assessment of aflatoxins and ochratoxin A in Egyptian wheat

Aflatoxins and ochratoxin A occur frequently in grains and are associated with carcinogenic, and nephrotoxic properties. Therefore, the aim of this study was to determine the level of aflatoxins and ochratoxin A contamination in wheat samples obtained from different Egyptian governorates and to assess the effect of gamma irradiation on AFB₁ in spiked wheat samples, as well as to evaluate the estimated daily intake and hazard index. Thirty-six wheat grain samples purchased from different sale points were analyzed by High-Performance Liquid Chromatography. Data revealed that 33.33 % of the wheat grain samples were contaminated by aflatoxin B₁, whereas only 16.66 % of the wheat samples were above the maximum limits (2 μg/kg) set by the European Commission. Ochratoxin A was only detected in two wheat grain samples, and the results were considered below the maximum limit (5 μg/kg) set by the European Commission. On studying the effect of gamma irradiation on wheat samples spiked by aflatoxin B₁ (20 μg/kg), results revealed that aflatoxin B₁ was reduced to 1.22 and 0.94 μg/kg for samples gamma-irradiated at a dose of 10 and 20 KGy respectively. Estimated daily intake of ochratoxin A in wheat samples was found to be higher than that of the tolerable daily intake; however, hazard index values were below one, thus demonstrating no threat to human health.

Safety evaluation of Ochratoxin A and Citrinin after 28 days repeated dose oral exposure to Wistar rats

Mycotoxins, ochratoxin A (OTA), and citrinin (CTN) are toxic metabolites of filamentous fungi. The most common fungal species that produce OTA and CTN belong to genera Aspergillus, Penicillium, Fusarium, and Monascus, and these fungal species are found to be contaminant a wide range of grains, food, and food product. The aim of our study was to evaluate the sub-acute repeated dose oral toxicity of OTA and CTN in experimental rodents by following OECD test guidelines for testing chemicals no. 407 with minor modifications. Twenty-five rats of each sex were divided equally into five groups; vehicle control, OTA 25 μg/kg b. wt., OTA 100 μg/kg b. wt., CTN 25 μg/kg b.wt. and CTN 100 μg/kg b. wt. The results of this study showed no abnormal clinical signs during 28 days of the experimental period. We did not found any significant changes in body weight gain, food consumption pattern, organ weight, hematology except few parameters, and biochemical values in any of the treatment and control groups. However, histopathological observations revealed severe nephrotoxicity and mild follicular depletion in the spleen of 100 μg/kg b. wt. treated groups of both OTA and CTN mycotoxins. The findings of our study are of its first kind that reports the systemic toxicity of OTA and CTN oral exposure to laboratory rodents.

Change of Amino Acid Residues in Idiotypic Nanobodies Enhanced the Sensitivity of Competitive Enzyme Immunoassay for Mycotoxin Ochratoxin A in Cereals

Anti-idiotypic nanobodies, usually expressed by gene engineering protocol, has been shown as a nontoxic coating antigen for toxic compound immunoassays. We here focused on how to increase immunoassay sensitivity by changing the nanobody’s primary sequence. In the experiments, two anti-idiotype nanobodies against monoclonal antibody 1H2, which is specific to ochratoxin A, were obtained and named as nontoxic coating antigen 1 (NCA1) and nontoxic coating antigen 2 (NCA2). Three differences between the nanobodies were discovered. First, there are six amino acid residues (AAR) of changes in the complementarity determining region (CDR), which compose the antigen-binding site. One of them locates in CDR1 (I–L), two of them in CDR2 (G–D, E–K), and three of them in CDR3 (Y–H, Y–W). Second, the affinity constant of NCA1 was tested as 1.20 × 10⁸ L mol⁻¹, which is about 4 times lower than that of NCA2 (5.36 × 10⁸ L mol⁻¹). Third, the sensitivity (50% inhibition concentration) of NCA1 for OTA was shown as 0.052 ng mL⁻¹, which was 3.5 times lower than that of nontoxic coating antigen 2 (0.015 ng mL⁻¹). The results indicate that the AAR changes in CDR of the anti-idiotypic nanobodies, from nonpolar to polar, increasing the affinity constant may enhance the immunoassay sensitivity. In addition, by using the nontoxic coating antigen 2 to substitute the routine synthetic toxic antigen, we established an eco-friendly and green enzyme-linked immunosorbent assay (ELISA) method for rapid detection of ochratoxin A in cereals. The half-maximal inhibitory concentration (IC₅₀) of optimized ELISA was 0.017 ng mL⁻¹ with a limit of detection (LOD) of 0.003 ng mL⁻¹. The optimized immunoassay showed that the average recoveries of spiked corn, rice, and wheat were between 80% and 114.8%, with the relative standard deviation (RSD) ranging from 3.1–12.3%. Therefore, we provided not only basic knowledge on how to improve the structure of anti-idiotype nanobody for increasing assay sensitivity, but also an available eco-friendly ELISA for ochratoxin A in cereals.

Eugenol protects against citrinin-induced cytotoxicity and oxidative damages in cultured human colorectal HCT116 cells

This study aimed to investigate the protective effects of Eugenol (EUG), an effective antioxidant phenolic compound with a radical scavenging activity against citrinin (CTN)-induced toxicity in vitro using HCT116 cells. CTN is a well-known mycotoxin found in different constituents of the food chain. This environmental contaminant produces free radicals which interacts with cellular macromolecules and produces oxidation of protein, lipid, and DNA. The cytotoxic effects were monitored by measuring cell viability, reactive oxygen species (ROS) generation, antioxidant enzyme activities, malondialdehyde (MDA) production, protein oxidation, and DNA fragmentation. Our results have shown that the pretreatment of HCT116 cells with EUG, 2 h prior to citrinin (CTN) exposure, significantly decreased CTN-induced cell death, inhibited ROS generation, modulated activities of both catalase (CAT) and superoxide dismutase (SOD), and reduced MDA production. Level of protein-bound sulfhydryls and DNA fragmentation were also declined as compared with CTN-treated cells. These findings suggest that EUG would be an effective protective agent against CTN-induced oxidative stress, and thereby, it may complement and add to the functions of antioxidant vitamins and enzymes as a protection against the cytotoxicity of this mycotoxin.

Effects of Gamma Irradiation on Ochratoxin A Stability and Cytotoxicity in Methanolic Solutions and Potential Application in Tunisian Millet Samples

Gamma irradiation is a useful technology for degrading mycotoxins. The purpose of this study was to investigate the effect of irradiation on ochratoxin A (OTA) stability under different conditions. OTA was irradiated in methanolic solution and on millet flour at doses of 2 and 4 kGy. Residual OTA concentrations and possible degradation products in irradiated samples were analyzed by high-performance liquid chromatography with fluorescence detection and liquid chromatography coupled to mass spectrometry. The extent of in vitro cytotoxicity of OTA to HepG2 cells, with and without irradiation treatment, was assessed with an MTT assay. OTA was more sensitive to gamma radiation on Tunisian millet flour than in methanolic solutions. After irradiation of naturally contaminated millet flour, the OTA concentration was significantly reduced by 48 and 62% at a dose of 2 and 4 kGy, respectively. However, in the methanolic solution, OTA at concentrations of 1 and 5 μg mL^-1 was relatively stable even at a dose of 4 kGy, with no degradation products detected in the chemical analysis. Analytical results were confirmed by cell culture assays. The remaining cytotoxicity (MTT assay) of OTA following irradiation was not significantly affected compared with the controls. These findings indicate that gamma irradiation could offer a solution for OTA decontamination in the postharvest processing chain of millet flour. However, the associated toxicological hazard of decontaminated food matrices needs more investigation.

Mycotoxin concentrations in rice from three climatic locations in Africa as affected by grain quality, production site, and storage duration

Information on the mycotoxin contamination of rice in Africa is limited although the risk of contamination is high. In this study, domestic milled rice processed by actors using suboptimal methods was purchased and total fumonisin (FUM), zearalenone, and aflatoxin concentrations determined at 0, 90, and 180 days after storage. Three different climatic locations, Cotonou (Benin) in the Guinea savanna, Yaoundé (Cameroon) in the Tropical forest, and N'diaye (Senegal) in the Sahel, were selected as storage sites. Subsets of the samples collected from Glazoue (Benin), Ndop (Cameroon), and Dagana (Senegal) were stored in plastic woven bags under room conditions in the respective sites with or without calcium oxide (burnt scallop shell-BSS, 0.1% w/w) treatment. Multivariance analysis showed that FUM concentration was positively influenced by the duration of storage only while zearalenone concentration was negatively influenced by relative humidity and head rice but positively by impurities. Zearalenone concentration was also influenced by sample collection/storage location, processing type, and duration of storage. Aflatoxin concentration was influenced negatively by storage room temperature and head rice but positively by impurities and chalky grains. In addition, aflatoxin concentration was influenced by collection/storage location and processing type. BSS treatment followed by storage for 6 months had no effect on the concentration of the three assessed mycotoxins. Strategies to reduce the risk of mycotoxin contamination in study sites will include the improvement of physical rice quality through better pre- and postharvest practices and proper packaging of both treated rice and untreated rice in hermetic systems before marketing and storage.

Toxigenic fungi and mycotoxin occurrence and prevention in food and feed in northern Africa – a review

North African countries (Algeria, Morocco and Tunisia) are surrounded by water bodies, such as the Mediterranean Sea and the Atlantic Ocean. Their climate is characterised by high temperatures and high relative humidity in some areas, which are environmental conditions favourable to fast fungal growth and toxinogenesis. This paper reports information on the presence of toxigenic fungi, mycotoxins (especially aflatoxins and ochratoxin A) and emerging Fusarium mycotoxins (enniatins, beauvericin and fusaproliferin) in some Northern African commodities that are largely consumed and were investigated thoroughly, especially raw cereals, bread, couscous, pasta, milk, spices, wine, beer, fruit juices, olives and olive oil, dried fruits and nuts, poultry feeds, etc. in the three North African countries. High contamination levels have been reported for some food samples from the three countries. Steps towards better prevention of mycotoxin production in feeds and decrease of intestinal absorption, by means of plant essential oils associated with clay, have been undertaken. Morocco presumably is the country where mycotoxin regulation is the most detailed in comparison with Algeria and Tunisia. Finally, the conclusion section offers some prospects and recommendations for actions by authorities and scientists during the monitoring of mycotoxins in the foods and feeds produced and/or commercialised in the three countries.

Aflatoxin B1, ochratoxin A and zearalenone in sorghum grains marketed in Tunisia

A total of 64 samples of sorghum (37 Tunisian sorghum samples and 27 Egyptian sorghum samples) were collected during 2011-2012 from markets in Tunisia. Samples were analysed for contamination with aflatoxin B1, ochratoxin A and zearalenone by High-Performance Liquid Chromatography Coupled with Fluorescence Detection (HPLC-FLD). Aflatoxin B1 was found in 38 samples in the range 0.03-31.7 µg kg^-1. Ochratoxin A was detected in 24 samples with concentrations ranging from 1.04 to 27.8 µg kg^-1. Zearalenone was detected in 21 samples and the concentration varied between 3.7 and 64.5 µg kg^-1. ANOVA analysis of the influence of the country of origin on the incidence and concentration of mycotoxins in the samples studied showed no significant difference (P > 0.05) between the two batches of samples for each of the three mycotoxins studied. The studied mycotoxins contaminate sorghum and may also co-exist because of the diversity of the mycobiota in this cereal.

Reduction of Ochratoxin A in Oat Flakes by Twin-Screw Extrusion Processing

Ochratoxin A (OTA) is one of the most important mycotoxins owing to its widespread occurrence and toxicity, including nephrotoxicity and potential carcinogenicity to humans. OTA has been detected in a wide range of agricultural commodities, including cereal grains and their processed products. In particular, oat-based products show a higher incidence and level of contamination. Extrusion cooking is widely used in the manufacturing of breakfast cereals and snacks and may reduce mycotoxins to varying degrees. Hence, the effects of extrusion cooking on the stability of OTA in spiked (100 μg/kg) oat flake was investigated by using a laboratory-scale twin-screw extruder with a central composite design. Factors examined were moisture content (20, 25, and 30% dry weight basis), temperature (140, 160, and 180°C), screw speed (150, 200, and 250 rpm), and die size (1.5, 2, and 3 mm). Both nonextruded and extruded samples were analyzed for reductions of OTA by high-performance liquid chromatography, coupled with fluorescence detection. The percentage of reductions in OTA in the contaminated oat flakes upon extrusion processing were in the range of 0 to 28%. OTA was partially stable during extrusion, with only screw speed and die size having significant effect on reduction (P < 0.005). The highest reduction of 28% was achieved at 180°C, 20% moisture, 250 rpm screw speed, and a 3-mm die with 193 kJ/kg specific mechanical energy. According to the central composite design analyses, up to 28% of OTA can be reduced by a combination of 162°C, 30% moisture, and 221 rpm, with a 3-mm die.

Worldwide Occurrence of Mycotoxins in Cereals and Cereal-Derived Food Products: Public Health Perspectives of Their Co-occurrence

Cereal grains and their processed food products are frequently contaminated with mycotoxins. Among many, five major mycotoxins of aflatoxins, ochratoxins, fumonisins, deoxynivalenol, and zearalenone are of significant public health concern as they can cause adverse effects in humans. Being airborne or soilborne, the cosmopolitan nature of mycotoxigenic fungi contribute to the worldwide occurrence of mycotoxins. On the basis of the global occurrence data reported during the past 10 years, the incidences and maximum levels in raw cereal grains were 55% and 1642 μg/kg for aflatoxins, 29% and 1164 μg/kg for ochratoxin A, 61% and 71,121 μg/kg for fumonisins, 58% and 41,157 μg/kg, for deoxynivalenol, and 46% and 3049 μg/kg for zearalenone. The concentrations of mycotoxins tend to be lower in processed food products; the incidences varied depending on the individual mycotoxins, possibly due to the varying stability during processing and distribution of mycotoxins. It should be noted that more than one mycotoxin, produced by a single or several fungal species, may occur in various combinations in a given sample or food. Most studies reported additive or synergistic effects, suggesting that these mixtures may pose a significant threat to public health, particularly to infants and young children. Therefore, information on the co-occurrence of mycotoxins and their interactive toxicity is summarized in this paper.

Influence of temperature, water activity and incubation time on fungal growth and production of ochratoxin A and zearalenone by toxigenic Aspergillus tubingensis and Fusarium incarnatum isolates in sorghum seeds

The major objective of this study was to describe the effect of water activity and temperature on radial growth and production of ochratoxin A (OTA) and zearalenone (ZEA) on sorghum grains of three Aspergillus tubingensis and three Fusarium incarnatum isolates. The water activity range was 0.91-0.99 a_w for F. incarnatum isolates and 0.88-0.99 a_w for A. tubingensis isolates. Temperatures of incubation were 15, 25 and 37°C for both species. Mycotoxin production was determined after 7, 14, 21 and 28days depending on the growth rate of the six isolates. Maximum growth rates (mm/day) were observed at 37°C and 0.99 a_w for A. tubingensis isolates and at 0.99 a_w and 25°C for F. incarnatum isolates. A. tubingensis was able to grow at 15°C only at the highest a_w levels (0.97 and 0.99 a_w). However, at this temperature F. incarnatum grew at 0.94 a_w. Optimum ochratoxin A production was observed at 0.97 a_w×37°C whereas optimal conditions for ZEA production varied from one isolate to another. Moreover, isolates of F. incarnatum from Tunisia do not require high a_w and temperature levels to yield maximum levels of ZEA. In general, our results showed that there is no correlation between the growth and production of ZEA in the case of F. incarnatum. This is the first study on the water activity and temperature effect on growth rate and ZEA production of F. incarnatum. Our results show that sorghum grains not only support growth but also OTA and ZEA production by A. tubingensis and F. incarnatum, respectively.

Aflatoxins and ochratoxin A and their Aspergillus causal species in Tunisian cereals

Occurrence of aflatoxins (AFs) AFB1, AFB2, AFG1, AFG2 and ochra toxin A (OTA) was studied in 65 samples of stored and freshly harvested wheat, barley and maize collected in Tunisia. The mycotoxins were simultaneously extracted and quantified by high performance liquid chromatography. Determination of AF-producing (section Flavi) and OTA-producing Aspergillus species (sections Nigri and Circumdati) was conducted in these samples by species-specific polymerase chain reaction (PCR). Results showed that most of maize samples were contaminated with AFs, data after storage showing lower values than those collected at harvest. All contaminated maize samples contained AFG1 and AFG2, among which 27.78% also had AFB1 and AFB2. This AFs pattern was consistent with the A. parasiticus toxin profile. A. flavus however showed the highest frequency in maize but was also found in barley and wheat where no AFs were detected. In contrast, OTA was neither found in maize nor in barley and only one wheat sample contained OTA. A. niger was the only OTA-producing species detected.

Heat Stability of Ochratoxin A in an Aqueous Buffered Model System

Ochratoxin A (OTA) represents one of the most widespread mycotoxins in agricultural commodities in the world and is considered a possible human carcinogen with its potent nephrotoxicity. OTA is stable under most food processing conditions; however, higher-temperature treatment may reduce OTA content in foods. Since OTA can be found in processed products destined for both human and animal consumption, factors affecting its stability or reduction during thermal processes were investigated here. The reduction of OTA was measured during various heating times (up to 60 min) at different temperatures (100, 125, 150, 175, and 200°C) in aqueous buffer solutions at different pHs (pH 4, 7, and 10). Quantification of OTA was carried out using high-performance liquid chromatography with fluorescence detection. The results showed that the rate and extent of OTA reduction were dependent on pH, processing time, and temperature; greater than 90% OTA reduction was achieved at 200°C for all treatments except pH 4. After processing under an alkaline condition (pH 10) at 100°C for 60 min, about 50% of the OTA was lost, while after 60 min under neutral and acidic conditions at 100°C, significant reductions of OTA were not shown.

Selective tools for the solid-phase extraction of Ochratoxin A from various complex samples: immunosorbents, oligosorbents, and molecularly imprinted polymers

The evolution of instrumentation in terms of separation and detection has allowed a real improvement of the sensitivity and the analysis time. However, the analysis of ultra-traces of toxins such as ochratoxin A (OTA) from complex samples (foodstuffs, biological fluids…) still requires a step of purification and of preconcentration before chromatographic determination. In this context, extraction sorbents leading to a molecular recognition mechanism appear as powerful tools for the selective extraction of OTA and of its structural analogs in order to obtain more reliable and sensitive quantitative analyses of these compounds in complex media. Indeed, immunosorbents and oligosorbents that are based on the use of immobilized antibodies and of aptamers, respectively, and that are specific to OTA allow its selective clean-up from complex samples with high enrichment factors. Similar molecular recognition mechanisms can also be obtained by developing molecularly imprinted polymers, the synthesis of which leads to the formation of cavities that are specific to OTA, thus mimicking the recognition site of the biomolecules. Therefore, the principle, the advantages, the limits of these different types of extraction tools, and their complementary behaviors will be presented. The introduction of these selective tools in miniaturized devices will also be discussed.

Assessment of ochratoxin A stability following gamma irradiation: experimental approaches for feed detoxification perspectives

The present study evaluated the effect of gamma irradiation on the stability of ochratoxin A (OTA) under various conditions. The effects of the physical state of OTA (solid vs aqueous), initial OTA concentration, irradiation dose and dose rate as well as the presence of model substances simulating food matrix compounds on OTA radiostability were investigated. First, pure OTA with and without food model compounds including α-D-glucose (monosaccharide), Methyl α-D-glucopyranoside (starch) and the amino acid derivatives N-α-acetyl-L-lysine methyl ester and N-α-acetyl-L-cysteine methyl ester (protein models) were irradiated with doses of 2, 4 and 8 kGy applied at 15.117 and 108.24 Gy/min. Secondly, artificially OTA-contaminated wheat with different moisture content (11, 14 and 16%) was irradiated with doses of 2, 4 and 8 kGy applied at 63.39 Gy/min. Residual OTA levels were analysed using ultra-high performance liquid chromatography coupled with tandem mass spectrometry. Solid OTA (50 and 3,200 ng/ml)showed great irradiation stability, even with irradiation doses up to 8 kGy. Under dry conditions, the presence of food model components did not affect OTA radiostability. However, in an aqueous solution, complete reduction was achieved at the initial OTA concentration of 50 ng/ml and irradiation dose of 2 kGy. Applying gamma irradiation to cereal-based food model systems produced a significant OTA reduction (5,000 µg/kg) of 47.2% in moistened wheat kernels (16%) with an absorbed dose of 8 kGy but failed to reduce the OTA content of low moisture content wheat (11%). These model experiments offered a useful tool to assess the main key factors affecting gamma irradiation-induced OTA reduction. Gamma irradiation is promising since the irradiation doses applied could partially reduce OTA contamination. Nevertheless, its efficacy was largely affected by initial moisture content and could be dangerous if toxic by-products are produced or nutritive quality is lost and needs further study.

The occurrence of ochratoxin A in rice in six provinces of Iran

Three hundred and eight samples of rice purchased from retail markets in six different provinces in Iran from March 2012 to January 2013 were surveyed for the presence of ochratoxin A (OTA) using enzyme-linked immunosorbent assay. The recovery percentages of OTA from spiked rice samples at concentrations of 5 and 10 ng/g were found to be 85.3% and 86.7%, respectively. Analytical results showed a 9.4% frequency of contamination from total analyzed rice samples with a mean OTA level of 3.60 ± 2.66 ng/g. Concentrations of OTA in positive samples ranged from 0.84 ng/g to 11.37 ng/g, and in 17.3% of contaminated rice samples the concentrations exceeded the maximum tolerance limit set by European regulations for OTA in cereals (5 ng/g). Based on the results of this study, the estimated daily intake of OTA in rice was 0.62 ng/kg body weight/day for Iranian consumers.

Ochratoxin A levels in spices and dried nuts consumed in Tunisia

A total of 112 samples of spices (24 caraway, 20 coriander, 25 curcuma, 20 black pepper and 23 red pepper) and 110 samples of dried nuts (44 almonds, 42 peanuts and 24 pistachio) purchased from popular markets in 24 regions of Tunisia were analyzed for ochratoxin A (OTA) by fluorescence HPLC. The average levels of contamination of OTA found in spice samples were 244, 206, 290, 274 and 203 µg/kg, respectively, for caraway, coriander, curcuma, black pepper and red pepper. Concerning dried nut samples, the average levels were 61, 60 and 89 µg/kg, respectively, for almonds, peanuts and pistachio. Contamination levels were higher than the usual norms (10.0 OTA µg/kg) established by the European Commission in 2005 . This survey is the first to be carried out on the natural occurrence of OTA in the main spices and dried nuts consumed by the Tunisian population.

Food safety management systems performance in African food processing companies: a review of deficiencies and possible improvement strategies

This study seeks to provide insight into current deficiencies in food safety management systems (FSMS) in African food-processing companies and to identify possible strategies for improvement so as to contribute to African countries' efforts to provide safe food to both local and international markets. This study found that most African food products had high microbiological and chemical contamination levels exceeding the set (legal) limits. Relative to industrialized countries, the study identified various deficiencies at government, sector/branch, retail and company levels which affect performance of FSMS in Africa. For instance, very few companies (except exporting and large companies) have implemented HACCP and ISO 22000:2005. Various measures were proposed to be taken at government (e.g. construction of risk-based legislative frameworks, strengthening of food safety authorities, recommend use of ISO 22000:2005, and consumers' food safety training), branch/sector (e.g. sector-specific guidelines and third-party certification), retail (develop stringent certification standards and impose product specifications) and company levels (improving hygiene, strict raw material control, production process efficacy, and enhancing monitoring systems, assurance activities and supportive administrative structures). By working on those four levels, FSMS of African food-processing companies could be better designed and tailored towards their production processes and specific needs to ensure food safety.

Characterization of oligosorbents and application to the purification of ochratoxin A from wheat extracts

The aim of this work was to optimize the preparation of an anti-ochratoxin A (OTA) oligosorbent (OS), a solid-phase extraction sorbent based on OTA aptamers covalently immobilized on sepharose. Different syntheses were carried out by modifying the side of the oligonucleotide chain bound to the sepharose, the length of the spacer arm between the aptamer and the sepharose and the amount of the aptamers introduced during the covalent grafting. Indeed, the capacity of OSs prepared using 3'- or 5'-amino-modified sequences with a C6 or a C12 was studied. In the best conditions, the concentration of aptamers sequence used during their grafting was increased and a capacity close to 40 nmol g(-1) of OS was reached. The potential of the resulting OSs was also studied in pure media. For this, their selectivity was checked by comparing them to a control sorbent prepared without immobilizing aptamers. Extraction recoveries close to 100% were obtained on all OSs, while no retention was observed on the control sorbent. OS does not demonstrate any cross-reactivity towards OTA metabolites, i.e., ochratoxin B and ochratoxin hydroquinone. The oligosorbent was finally applied to the clean-up of OTA from wheat sample extracts. Extraction recoveries were not affected by matrix interferences and the resulting chromatogram clearly highlights the selectivity of the sorbent that allows the removal of matrix components thus improving the reliability of the quantitation of OTA in real samples.

Ochratoxin A in several grains in Iran

Ochratoxin A content in 100 grain and derived products were determined by high-performance liquid chromatography with immunoaffinity column clean-up and fluorometric detection. Ochratoxin A was detected in 32% of green gram, 13.3% of chickpea, 10% of lentil and 17.5% of wheat flour. Ochratoxin contamination was below the regulatory limits of the European Union and of Iran. Recovery was 97% and the limit of detection was 0.12 ng g⁻¹.

Molecular events involved in ochratoxin A induced mitochondrial pathway of apoptosis, modulation by Bcl-2 family members

In this study, we looked for the role of the mitochondrion in the cytotoxicity of ochratoxin A (OTA), which is one of the most abundant food-contaminating mycotoxins in the world. In different human carcinoma cell lines, OTA triggered a mitochondria-dependent apoptotic process, which is characterized by opening of the mitochondrial permeability transition pore (PTPC), loss of mitochondrial transmembrane potential (ΔΨ(m) ), increase in O(2) [chemp](-) production, mitochondrial relocalization of Bax, release of cytochrome c, and caspase activation. However, studies performed on purified organelles suggested that OTA does not directly target the mitochondrion. In addition, we showed that mitochondrial alterations induced by this mycotoxin are favored by the proapoptotic protein Bax, but not Bak. These alterations are prevented by the antiapoptotic proteins, Bcl-2 and to a lesser degree by Bcl-X(L). Taken together, these data indicate that although mitochondria, PTPC members and proteins of Bcl-2 family play a pivotal role in OTA-induced apoptosis, they do not constitute real targets to overcome its toxicity.