Analysis of heat-processed corn foods for fumonisins and bound fumonisins

Interaction of Fumonisin B1, N-Palmitoyl-Fumonisin B1, 5-O-Palmitoyl-Fumonisin B1, and Fumonisin B4 Mycotoxins with Human Serum Albumin and Their Toxic Impacts on Zebrafish Embryos

Fumonisins are frequent food contaminants. The high exposure to fumonisins can cause harmful effects in humans and animals. Fumonisin B1 (FB1) is the most typical member of this group; however, the occurrence of several other derivatives has been reported. Acylated metabolites of FB1 have also been described as possible food contaminants, and the very limited data available suggest their significantly higher toxicity compared to FB1. Furthermore, the physicochemical and toxicokinetic properties (e.g., albumin binding) of acyl-FB1 derivatives may show large differences compared to the parent mycotoxin. Therefore, we tested the interactions of FB1, N-palmitoyl-FB1 (N-pal-FB1), 5-O-palmitoyl-FB1 (5-O-pal-FB1), and fumonisin B4 (FB4) with human serum albumin as well as the toxic effects of these mycotoxins on zebrafish embryos were examined. Based on our results, the most important observations and conclusions are the following: (1) FB1 and FB4 bind to albumin with low affinity, while palmitoyl-FB1 derivatives form highly stable complexes with the protein. (2) N-pal-FB1 and 5-O-pal-FB1 likely occupy more high-affinity binding sites on albumin. (3) Among the mycotoxins tested, N-pal-FB1 showed the most toxic effects on zebrafish, followed by 5-O-pal-FB1, FB4, and FB1. (4) Our study provides the first in vivo toxicity data regarding N-pal-FB1, 5-O-pal-FB1, and FB4.

Matrix-associated mycotoxins in foods, cereals and feedstuffs: A review on occurrence, detection, transformation and future challenges

Matrix-associated mycotoxins that bind with macromolecular components through covalent or non-covalent interactions easily occur in various cereals, cereal-based products, and cereal-based feedstuff. They are "masked" by macro-components, causing the underestimation of total exposure risk of mycotoxins. Most of the current reports focus on the free and modified mycotoxins, while the matrix-associated forms are ignored but still can exert toxic effects after ingestion. In this paper, current researches and future prospects of matrix-associated mycotoxins are reviewed. Especially, a focus is set on the transformation of matrix-associated mycotoxins with their free forms during metabolism and food processing. Enzymes, temperature and pH levels during food processing can induce the interconversion of matrix-associated mycotoxins with free mycotoxins. Furthermore, the analytical methods targeted on matrix-associated mycotoxins are discussed. Due to the lack of efficient methods releasing the mycotoxins from matrix, the standard analytical methods has not developed so far. Also, we further analyzed the challenges of matrix-associated mycotoxins about variety, occurrence, toxicity and transformation, exposure assessment, which contributes to establish preventive measures to control their hazards for consumers. Overall, this overview is significant for perfecting risk assessment, as well as developing effective prevention and control actions to matrix-associated mycotoxins.

Preparation of 3-O-, 5-O- and N-palmitoyl derivatives of fumonisin B1 toxin and their characterisation with NMR and LC-HRMS methods

We have previously published six esterified O-acyl (EFB1) and three N-acyl fumonisin B₁ derivatives extracted from rice cultures inoculated with Fusarium verticillioides, amongst these the identification of N-palmitoyl-FB1 has been clearly established in a spiking experiment. At that time, it was assumed that as in the case of O-acyl-FB1 derivatives, linoleic-, oleic- or palmitic acid esterify through the OH group on the 3C or 5C atom of the carbon chain of the fumonisins. In our most recent experiments, we have synthetically acylated the FB1 toxin and subsequently purified 3-O-palmitoyl- and 5-O-palmitoyl-FB1 toxins in addition to the N-palmitoyl-FB1 toxin. They were identified and characterised using ¹H and ¹³C NMR as well as LC-HRMS. Our aim was the identification of the previously detected O-acyl-FB1 derivatives over the course of a spiking experiment, which were obtained through the solid-phase fermentation of Fusarium verticillioides. By spiking the three synthesized and identified components one-by-one into the fungal culture extract and analysing these cultures using LC-MS, it was clearly demonstrated that the F. verticillioides strain produced both the 5-O-palmitoyl-FB1 and N-palmitoyl-FB1 toxins, but did not produce 3-O-palmitoyl-FB1. Thus, it is highly probable that the components thought to be 3-O-acyl-(linoleoyl-, oleoyl-, palmitoyl-) FB1 derivatives in our previous communication are presumably 10-O-acyl-FB1 derivatives. Since these acylated FB1 derivatives can occur naturally in e.g. maize, the use of these synthesized components as reference materials is of great importance in order to obtain accurate qualitative and quantitative data on the occurrence of acylated fumonisins in different matrices including maize based feed samples. The production of these substances has also made it possible to test their toxicity in cell culture and small animal experiments.

Mycotoxins along the tea supply chain: A dark side of an ancient and high valued aromatic beverage

ABSTRACTSTea (Camellia sinensis L.) is a high valued beverage worldwide since ancient times; more than three billion cups of tea are consumed each day. Leaf extracts of the plant are used for food preservation, cosmetics, and medicinal purposes. Nevertheless, tea contaminated with mycotoxins poses a serious health threat to humans. Mycotoxin production by tea fungi is induced by a variety of factors, including poor processing methods and environmental factors such as high temperature and humidity. This review summarizes the studies published to date on mycotoxin prevalence, toxicity, the effects of climate change on mycotoxin production, and the methods used to detect and decontaminate tea mycotoxins. While many investigations in this domain have been carried out on the prevalence of aflatoxins and ochratoxins in black, green, pu-erh, and herbal teas, much less information is available on zearalenone, fumonisins, and Alternaria toxins. Mycotoxins in teas were detected using several methods; the most commonly used being the High-Performance Liquid Chromatography (HPLC) with fluorescence detection, followed by HPLC with tandem mass spectrometry, gas chromatography and enzyme-linked immunosorbent assay. Further, mycotoxins decontamination methods for teas included physical, chemical, and biological methods, with physical methods being most prevalent. Finally, research gaps and future directions have also been discussed.

Fusarium Mycotoxins, Their Metabolites (Free, Emerging, and Masked), Food Safety Concerns, and Health Impacts

The genus Fusarium produces a number of mycotoxins of diverse chemical structures. Fusariotoxins are secondary metabolites produced by toxigenic fungi of the genus Fusarium. The important and commonly encountered fusariotoxins are trichothecenes, fumonisins, and zearalenone. Fusarium mycotoxins pose varying toxicities to humans and/or animals after consumption of contaminated grain. They can cause acute or chronic illness and, in some cases, death. For instance, a range of Fusarium mycotoxins can alter different intestinal defense mechanisms, such as the epithelial integrity, cell proliferation, mucus layer, immunoglobulins, and cytokine production. Of recent concern is the occurrence of emerging and masked Fusarium mycotoxins in agricultural commodities, which may contribute to toxic health effects, although the metabolic fate of masked mycotoxins still remains a matter of scientific discussion. These mycotoxins have attracted attention worldwide because of their impact on human and animal health, animal productivity, and the associated economic losses. In this paper, we review Fusarium mycotoxins and their metabolites with the aim of summarizing the baseline information on the types, occurrence, and health impacts of these mycotoxins in order to encourage much-needed research on integrated management of this unavoidable food contaminant as concerns for food safety continues to grow worldwide.

Stability of fumonisin B1 and its bioaccessibility in extruded corn-based products

Fumonisins are a group of mycotoxins commonly associated with corn-based products and require innovative alternatives to control exposure to its toxicity. The objective of this research was to determine the effect of amylose and resistant starch on fumonisin B1 (FB₁) levels in extruded corn-based products as well as the toxin bioaccessibility upon digestion. Cornmeal contaminated with FB₁ (1.5 µg/g) was extruded alone or combined with high-amylose corn starch (20%, w/w). FB₁ was quantified both in the unextruded and extruded products by HPLC (high-performance liquid chromatography) fluorescence detector with pre-column derivatization. Samples were then subjected to an in vitro digestion model to evaluate the stability of the interaction between FB₁ and the corn matrix extruded. The addition of high-amylose corn starch further reduced the detection of FB₁ (74.9%), when compared with the effect of the extrusion alone (66.0%), confirming the binding of FB₁ with the macromolecules or resistant starch. The bound fumonisin was stable upon simulated gastric digestion, and the duodenal bioaccessibility of free FB₁ was lower than 35% when high-amylose corn starch ingredient was used in the product. Principal component analysis (PCA) showed that high-amylose corn starch and resistant starch content influenced the reduction of FB₁ and its duodenal bioaccessibility. This study for the first time shows that addition of high-amylose corn starch during extrusion is an innovative strategy to reduce FB₁ release under digestive conditions, therefore useful in mitigating the exposure to this mycotoxin.

Mycotoxins Analysis in Cereals and Related Foodstuffs by Liquid Chromatography-Tandem Mass Spectrometry Techniques

In the entire world, cereals and related foodstuffs are used as an important source of energy, minerals, and vitamins. Nevertheless, their contamination with mycotoxins kept special attention due to harmful effects on human health. The present paper was conducted to evaluate published studies regarding the identification and characterization of mycotoxins in cereals and related foodstuffs by liquid chromatography coupled to (tandem) mass spectrometry (LC-MS/MS) techniques. For sample preparation, published studies based on the development of extraction and clean-up strategies including solid-phase extraction, solid-liquid extraction, and immunoaffinity columns, as well as on methods based on minimum clean-up (quick, easy, cheap, effective, rugged, and safe (QuEChERS)) technology, are examined. LC-MS/MS has become the golden method for the simultaneous multimycotoxin analysis, with different sample preparation approaches, due to the range of different physicochemical properties of these toxic products. Therefore, this new strategy can be an alternative for fast, simple, and accurate determination of multiclass mycotoxins in complex cereal samples.

The fate of mycotoxins during secondary food processing of maize for human consumption

Mycotoxins are naturally occurring fungal metabolites that are associated with health hazards and are widespread in cereals including maize. The most common mycotoxins in maize that occur at relatively high levels are fumonisins (FBs), zearalenone, and aflatoxins; furthermore, other mycotoxins such as deoxynivalenol and ochratoxin A are frequently present in maize. For these toxins, maximum levels are laid down in the European Union (EU) for maize raw materials and maize-based foods. The current review article gives a comprehensive overview on the different mycotoxins (including mycotoxins not regulated by EU law) and their fate during secondary processing of maize, based on the data published in the scientific literature. Furthermore, potential compliance with the EU maximum levels is discussed where appropriate. In general, secondary processing can impact mycotoxins in various ways. Besides changes in mycotoxin levels due to fractionation, dilution, and/or concentration, mycotoxins can be affected in their chemical structure (causing degradation or modification) or be released from or bound to matrix components. In the current review, a special focus is set on the effect on mycotoxins caused by different heat treatments, namely, baking, roasting, frying, (pressure) cooking, and extrusion cooking. Production processes involving multiple heat treatments are exemplified with the cornflakes production. For that, potential compliance with FB maximum levels was assessed. Moreover, effects of fermentation of maize matrices and production of maize germ oil are covered by this review.

[Assessment of Modified Forms of Fumonisins in Corn-Based Products Retailed in Japan by an Alkaline Hydrolysis Method]

Fumonisins, which are secondary metabolites produced by some Fusarium species, are detected mainly in corn and corn-based products. Recently, the presence of modified forms of fumonisins in fumonisin-contaminated food products has been reported. In order to evaluate the health risk of modified forms of fumonisins to the Japanese population, we analyzed modified forms of fumonisins in corn-based products retailed in Japan. The modified and free forms of fumonisins in food samples were hydrolyzed by alkaline treatment. The resulting hydrolyzed fumonisins were quantified by LC-MS/MS, and total fumonisins (sum of modified and free forms) was calculated. A total of 166 samples of corn-based products were analyzed over two years. The relative ratios of mean total fumonisins to mean free fumonisins in the cornflakes, corn snacks, corn flour and powdered corn soup samples were 4.7, 2.8, 2.1 and 1.2, respectively. Total fumonisins in the residual solid of five cornflake and three corn snack samples obtained after extraction with methanol-water (3 : 1) were quantified. In the cornflakes and corn snacks samples, 56-72 and 83-98% of the modified forms of fumonisins were present in the residual solid, respectively. The average daily intake of fumonisins from cornflakes and corn snacks by the Japanese population was estimated at 1.1 to 3.9 ng/kg body weight/day when the results of free fumonisins were used for the estimate, but when the results of total fumonisins were used, average daily intake increased about three times and was estimated at 3.3 to 12.5 ng/kg body weigh/day. These results indicate that a risk assessment of fumonisins, including the modified forms of fumonisins, is necessary in order to evaluate the true risk of fumonisins to Japanese people.

Mycotoxins during the Processes of Nixtamalization and Tortilla Production

Tortillas are a traditional staple food in Mesoamerican cuisine, which have also become popular on a global level, e.g., for wraps or as snacks (tortilla chips). Traditional tortilla production includes alkaline cooking (nixtamalization) of maize kernels. This article summarizes the current knowledge on mycotoxin changes during the nixtamalization of maize and tortilla production. Upon nixtamalization, mycotoxins can be affected in different ways. On the one hand, the toxins can be physically removed during steeping and washing. On the other hand, mycotoxins might be degraded, modified, or released/bound in the matrix by high pH and/or high temperature. This also applies to the subsequent baking of tortillas. Many studies have shown reduced mycotoxin levels in alkali-cooked maize and in tortillas. Most of the available data relate to aflatoxins and fumonisins. The reduction (and detoxification) of aflatoxins during nixtamalization might, however, be partially reversed in acidic conditions. The loss of fumonisin concentrations is to some extent accompanied by hydrolyzation and by lower toxicity. However, some studies have indicated the potential formation of toxicologically relevant modified forms and matrix-associated fumonisins. More data are required to assess the influence of alkaline cooking regarding such modified forms, as well as mycotoxins other than aflatoxins/fumonisins.

Fumonisins and their analogues in contaminated corn and its processed foods - a review

One of the food security problems faced worldwide is the occurrence of mycotoxins in grains and their foods. Fumonisins (FBs) are mycotoxins which are prevalent in corn (Zea mays L.) and its based foods. Their intake and exposure have been epidemiologically and inconclusively associated with oesophageal cancer and neural tube defects in humans, and other harmful health effects in animals. The toxic effects of FBs can be acute or chronic and these metabolites bioaccumulate mainly in liver and kidney tissues. Among FBs, fumonisin B₁ (FB₁) is the most relevant moiety although the 'hidden' forms produced after food thermal processes are becoming relevant. Corn is the grain most susceptible to Fusarium and FBs contamination and the mould growth is affected both by abiotic and biotic factors during grain maturation and storage. Mould counts are mainly affected by the grain water activity, the environmental temperature during grain maturation and insect damage. The abiotic factors affected by climatic change patterns have increased their incidence in other regions of the world. Among FBs, the hidden forms are the most difficult to detect and quantify. Single or combined physical, chemical and biological methods are emerging to significantly reduce FBs in processed foods and therefore diminish their toxicological effects.

Appropriateness to set a group health-based guidance value for fumonisins and their modified forms

The EFSA Panel on Contaminants in the Food Chain (CONTAM) established a tolerable daily intake (TDI) for fumonisin B1 (FB 1) of 1.0 μg/kg body weight (bw) per day based on increased incidence of megalocytic hepatocytes found in a chronic study with mice. The CONTAM Panel considered the limited data available on toxicity and mode of action and structural similarities of FB 2-6 and found it appropriate to include FB 2, FB 3 and FB 4 in a group TDI with FB 1. Modified forms of FBs are phase I and phase II metabolites formed in fungi, infested plants or farm animals. Modified forms also arise from food or feed processing, and include covalent adducts with matrix constituents. Non-covalently bound forms are not considered as modified forms. Modified forms of FBs identified are hydrolysed FB 1-4 (HFB 1-4), partially hydrolysed FB 1-2 (pHFB 1-2), N-(carboxymethyl)-FB 1-3 (NCM-FB 1-3), N-(1-deoxy-d-fructos-1-yl)-FB 1 (NDF-FB 1), O-fatty acyl FB 1, N-fatty acyl FB 1 and N-palmitoyl-HFB 1. HFB 1, pHFB 1, NCM-FB 1 and NDF-FB 1 show a similar toxicological profile but are less potent than FB 1. Although in vitro data shows that N-fatty acyl FBs are more toxic in vitro than FB 1, no in vivo data were available for N-fatty acyl FBs and O-fatty acyl FBs. The CONTAM Panel concluded that it was not appropriate to include modified FBs in the group TDI for FB 1-4. The uncertainty associated with the present assessment is high, but could be reduced provided more data are made available on occurrence, toxicokinetics and toxicity of FB 2-6 and modified forms of FB 1-4.

Modified mycotoxins: An updated review on their formation, detection, occurrence, and toxic effects

Modified mycotoxins are metabolites that normally remain undetected during the testing for parent mycotoxin. These modified forms of mycotoxins can be produced by fungi or generated as part of the defense mechanism of the infected plant. In some cases, they are formed during food processing. The various processing steps greatly affect mycotoxin levels present in the final product (free and modified), although the results are still controversial regarding the increase or reduction of these levels, being strongly related to the type of process and the composition of the food in question. Evidence exists that some modified mycotoxins can be converted into the parent mycotoxin during digestion in humans and animals, potentially leading to adverse health effects. Some of these formed compounds can be even more toxic, in case they have higher bioaccessibility and bioavailability than the parent mycotoxin. The modified mycotoxins can occur simultaneously with the free mycotoxin, and, in some cases, the concentration of modified mycotoxins may exceed the level of free mycotoxin in processed foods. Even though toxicological data are scarce, the possibility of modified mycotoxin conversion to its free form may result in a potential risk to human and animal health. This review aims to update information on the formation, detection, occurrence, and toxic effects caused by modified mycotoxin.

Yeast and bacteria from ensiled high moisture maize grains as potential mitigation agents of fumonisin B1

BACKGROUND

Fumonisin B₁ (FB₁ ) is a mycotoxin produced by several Fusarium species and is a very common contaminant of maize-based food and feed throughout the world. The selection and use of FB₁ -degrading microorganisms appears as a promising alternative to cope with the problem of toxicity towards humans and livestock. High moisture maize grain silage, which is based on natural maize fermentation, could be an interesting reservoir of such microorganisms.

RESULTS

Using an in vitro simulated silage model with FB₁ naturally contaminated grains, we demonstrated a significant raw decrease in FB₁ during ensiling process ascribed to biodegradation mechanisms. A panel of 98 bacteria and yeasts were isolated from this matrix and selected for their ability to use FB₁ as the sole source of C and N. For nine of them, the ability to degrade FB₁ in vitro was evidenced. Notably, two bacteria identified as Lactobacillus sp. were highlighted for their efficient FB₁ -degrading capacity and production of hydrolysed FB₁ as intermediate degradation metabolite.

CONCLUSION

Fermentation of high moisture maize grain contaminated with FB₁ leads to a significant reduction of the toxin and allows the isolation of FB₁ -degrading microorganisms that could further be used as FB₁ decontaminating agents. © 2016 Society of Chemical Industry.

Mycotoxin Decontamination of Food: Cold Atmospheric Pressure Plasma versus "Classic" Decontamination

Mycotoxins are secondary metabolites produced by several filamentous fungi, which frequently contaminate our food, and can result in human diseases affecting vital systems such as the nervous and immune systems. They can also trigger various forms of cancer. Intensive food production is contributing to incorrect handling, transport and storage of the food, resulting in increased levels of mycotoxin contamination. Mycotoxins are structurally very diverse molecules necessitating versatile food decontamination approaches, which are grouped into physical, chemical and biological techniques. In this review, a new and promising approach involving the use of cold atmospheric pressure plasma is considered, which may overcome multiple weaknesses associated with the classical methods. In addition to its mycotoxin destruction efficiency, cold atmospheric pressure plasma is cost effective, ecologically neutral and has a negligible effect on the quality of food products following treatment in comparison to classical methods.

The Status of Fusarium Mycotoxins in Sub-Saharan Africa: A Review of Emerging Trends and Post-Harvest Mitigation Strategies towards Food Control

Fusarium fungi are common plant pathogens causing several plant diseases. The presence of these molds in plants exposes crops to toxic secondary metabolites called Fusarium mycotoxins. The most studied Fusarium mycotoxins include fumonisins, zearalenone, and trichothecenes. Studies have highlighted the economic impact of mycotoxins produced by Fusarium. These arrays of toxins have been implicated as the causal agents of wide varieties of toxic health effects in humans and animals ranging from acute to chronic. Global surveillance of Fusarium mycotoxins has recorded significant progress in its control; however, little attention has been paid to Fusarium mycotoxins in sub-Saharan Africa, thus translating to limited occurrence data. In addition, legislative regulation is virtually non-existent. The emergence of modified Fusarium mycotoxins, which may contribute to additional toxic effects, worsens an already precarious situation. This review highlights the status of Fusarium mycotoxins in sub-Saharan Africa, the possible food processing mitigation strategies, as well as future perspectives.

Occurrence of Fusarium Mycotoxins in Cereal Crops and Processed Products (Ogi) from Nigeria

In Nigeria, maize, sorghum, and millet are very important cash crops. They are consumed on a daily basis in different processed forms in diverse cultural backgrounds. These crops are prone to fungi infestation, and subsequently may be contaminated with mycotoxins. A total of 363 samples comprising of maize (136), sorghum (110), millet (87), and ogi (30) were collected from randomly selected markets in four agro-ecological zones in Nigeria. Samples were assessed for Fusarium mycotoxins contamination using a multi-mycotoxin liquid chromatography-tandem mass spectrometry (LC-MS/MS) method. Subsequently, some selected samples were analysed for the occurrence of hidden fumonisins. Overall, 64% of the samples were contaminated with at least one toxin, at the rate of 77%, 44%, 59%, and 97% for maize, sorghum, millet, and ogi, respectively. Fumonisins were the most dominant, especially in maize and ogi, occurring at the rate of 65% and 93% with mean values of 935 and 1128 μg/kg, respectively. The prevalence of diacetoxyscirpenol was observed in maize (13%), sorghum (18%), and millet (29%), irrespective of the agro-ecological zone. Other mycotoxins detected were deoxynivalenol, zearalenone, and their metabolites, nivalenol, fusarenon-X, HT-2 toxin, and hidden fumonisins. About 43% of the samples were contaminated with more than one toxin. This study suggests that consumption of cereals and cereal-based products, ogi particularly by infants may be a source of exposure to Fusarium mycotoxins.

Fumonisins and their modified forms, a matter of concern in future scenario?

Masked mycotoxins are found in grains and derived foods as a result of plant phase II metabolism. Recently, masked mycotoxins senso strictu, together with other covalently or non-covalently conjugated forms, even formed upon processing, have been classified as modified mycotoxins. In this context, the issue of modified fumonisins is of great interest, on account of the wide range of factors affecting their formation and accumulation in maize pre- and postharvest. Fumonisins, indeed, may undergo modification in plants, along the growing season, but also during storage and drying of maize kernels, and upon processing. All these modifications strongly affect the analytical outcome, thus making more difficult the assessment of maize compliance. Since the ratio between free and modified fumonisins is affected by maize composition and environmental factors, a deeper knowledge on the phenomena driving the production and accumulation of free and modified forms in plants may support the selection of resistant hybrids. This review provides a critical picture of the state of the art on this topic, mainly focusing on those events occurring in field, identified as crucial in determining amount and partitioning of contamination. Nevertheless, knowledge on modified fumonisins is still in its dawn, on account of the wide range of factors involved. Anyway, reported results, taking altogether, clearly indicate that modified fumonisins should be included in the monitoring plans to have an overview of the possible contribution to human exposure. Furthermore, next efforts should focus on the events occurring in field and on the cross-talk between the plant and the fungus, to support the identification of resistant hybrids and to provide data for predictive models, the most suitable tool to forecast what is going to happens in the future changing climate.

Advances in Mycotoxin Research: Public Health Perspectives

Aflatoxins, ochratoxins, fumonisins, deoxynivalenol, and zearalenone are of significant public health concern as they can cause serious adverse effects in different organs including the liver, kidney, and immune system in humans. These toxic secondary metabolites are produced by filamentous fungi mainly in the genus Aspergillus, Penicillium, and Fusarium. It is challenging to control the formation of mycotoxins due to the worldwide occurrence of these fungi in food and the environment. In addition to raw agricultural commodities, mycotoxins tend to remain in finished food products as they may not be destroyed by conventional processing techniques. Hence, much of our concern is directed to chronic health effects through long-term exposure to one or multiple mycotoxins from contaminated foods. Ideally risk assessment requires a comprehensive data, including toxicological and epidemiological studies as well as surveillance and exposure assessment. Setting of regulatory limits for mycotoxins is considered necessary to protect human health from mycotoxin exposure. Although advances in analytical techniques provide basic yet critical tool in regulation as well as all aspects of scientific research, it has been acknowledged that different forms of mycotoxins such as analogs and conjugated mycotoxins may constitute a significant source of dietary exposure. Further studies should be warranted to correlate mycotoxin exposure and human health possibly via identification and validation of suitable biomarkers.

Effect of alkaline cooking of maize on the content of fumonisins B1 and B2 and their hydrolysed forms

The effect of nixtamalization on the content of fumonisins (FBs), hydrolysed (HFBs) and partially hydrolysed (PHFBs) fumonisins in maize was investigated at laboratory-scale. Maize naturally contaminated with FBs and PHFBs was cooked with lime. Starting raw maize, steeping and washing waters and final masa fractions were analysed for toxin content. Control-cooking experiments without lime were also carried out. The nixtamalization reduced the amount of FBs and PHFBs in masa and converted them to HFBs. However, the three forms of fumonisins collected in all fractions amounted to 183%, indicating that nixtamalization made available forms of matrix-associated fumonisins that were then converted to their hydrolysed forms. Control-cooking enhanced FBs and PHFBs reduction, due to the solubility of fumonisins in water during the steeping process, but did not form HFBs. These findings indicate that benefits associated with enhancing the nutritional value of nixtamalized maize are also associated with a safer product in terms of fumonisin contamination.

Occurrence and stability of masked fumonisins in corn silage samples

Corn plants contaminated with Fusarium verticilloides were harvested at two dates and ensiled in laboratory silos. The stability of Fumonisins B1 and B2 (FB1, FB2) was studied and the effects of inoculant use (Lactobacillus buchneri) and of the ensiling time were assessed. The occurrence of masked fumonisins was also investigated. After the extraction of the free forms (FB1, FB2), the residue was subjected to an alkaline hydrolysis resulting in the release of derivates subsequently detected by LC-HESI-MS/MS. The ensiling time has shown to be a significant factor for the evolution of free FB1 and FB2 at the 2nd harvest date. Moreover, the use of inoculant had a significant effect on the stability of hidden and total FB1 at the two harvest dates. Samples previously ensiled and exposed to aerobic conditions for 7days have shown higher fumonisin levels than those not exposed to air. Our results showed that 65% and 39% of the total FB1 and FB2 contents in silage were due to hidden fumonisins.

Fumonisins in conventional and transgenic, insect-resistant maize intended for fuel ethanol production: implications for fermentation efficiency and DDGS co-product quality

Mycotoxins in maize grain intended for ethanol production are enriched in co-product dried distiller's grains and solubles (DDGS) and may be detrimental to yeast in fermentation. This study was conducted to examine the magnitude of fumonisin enrichment in DDGS and to analyze the impacts of insect injury, Fusarium ear rot severity, and fumonisin contamination on final ethanol yield. Samples of naturally-contaminated grain (0 to 35 mg/kg fumonisins) from field trials conducted in 2008-2011 were fermented and DDGS collected and analyzed for fumonisin content. Ethanol yield (determined gravimetrically) was unaffected by fumonisins in the range occurring in this study, and was not correlated with insect injury or Fusarium ear rot severity. Ethanol production was unaffected in fumonisin B1-spiked grain with concentrations from 0 to 37 mg/kg. Bacillus thuringiensis (Bt) maize often has reduced fumonisins due to its protection from insect injury and subsequent fungal infection. DDGS derived from Bt and non-Bt maize averaged 2.04 mg/kg and 8.25 mg/kg fumonisins, respectively. Fumonisins were enriched by 3.0× for 50 out of 57 hybrid × insect infestation treatment combinations; those seven that differed were <3.0 (1.56 to 2.56×). This study supports the industry assumption of three-fold fumonisin enrichment in DDGS, with measurements traceable to individual samples. Under significant insect pest pressures, DDGS derived from Bt maize hybrids were consistently lower in fumonisins than DDGS derived from non-Bt hybrids.

Use of liquid chromatography-high-resolution mass spectrometry for isolation and characterization of hydrolyzed fumonisins and relevant analysis in maize-based products

The synthesis of partially hydrolyzed fumonisins (PHFB1 and PHFB2) and hydrolyzed fumonisins (HFB1 and HFB2) by chemical hydrolysis of pure fumonisins (FB1 and FB2) is reported together with the isolation and characterization by liquid chromatography-high-resolution mass spectrometry (LC-HRMS). Two structural isomers of partially hydrolyzed forms of FB1 and FB2 were identified, namely PHFB(1a) and PHFB(1b) and PHFB(2a) and PHFB(2b). Reaction yields were 21% for PHFB1 (sum of the two isomers), 52% for HFB1, 31% for PHFB2 (sum of the two isomers) and 30% for HFB2. Purity of each isolated compound was >98%. An LC-HRMS method for the simultaneous determination of fumonisins and their partially and totally hydrolyzed derivatives was applied to 24 naturally contaminated samples of maize and maize-based products. The majority of samples (18 out of 24) were contaminated with fumonisins B1 and B2. Fumonisins co-occurred with both partially hydrolyzed and hydrolyzed fumonisins in four nixtamalized samples (three masa flours and one tortilla chips). Co-occurrence of fumonisins with partially hydrolyzed fumonisins was also recorded in one sample of maize kernels and four samples of maize-based products (i.e. maize meal, cous-cous, corn-cakes and cornflakes). Mycotoxins levels ranged from 60 to 5700 µg/kg for fumonisins (sum of FB1 and FB2), from 10 to 210 µg/kg for partially hydrolyzed fumonisins (sum of PHFB1 and PHFB2) and from 30 to 200 µg/kg for hydrolyzed fumonisins (sum of HFB1 and HFB2). This is the first report of the isolation of PHFB2 and the co-occurrence of FB1, FB2, PHFB1, PHFB2, HFB1 and HFB2 in maize products. Considering the growing use of nixtamalized and maize-based products, the monitoring of fumonisins and their partially and totally hydrolyzed forms in these products may represent an important contributing factor in evaluating the relevant human risk exposure.

Advanced hyphenated chromatographic-mass spectrometry in mycotoxin determination: current status and prospects

Mass spectrometric techniques are essential for advanced research in food safety and environmental monitoring. These fields are important for securing the health of humans and animals, and for ensuring environmental security. Mycotoxins, toxic secondary metabolites of filamentous fungi, are major contaminants of agricultural products, food and feed, biological samples, and the environment as a whole. Mycotoxins can cause cancers, nephritic and hepatic diseases, various hemorrhagic syndromes, and immune and neurological disorders. Mycotoxin-contaminated food and feed can provoke trade conflicts, resulting in massive economic losses. Risk assessment of mycotoxin contamination for humans and animals generally depends on clear identification and reliable quantitation in diversified matrices. Pioneering work on mycotoxin quantitation using mass spectrometry (MS) was performed in the early 1970s. Now, unambiguous confirmation and quantitation of mycotoxins can be readily achieved with a variety hyphenated techniques that combine chromatographic separation with MS, including liquid chromatography (LC) or gas chromatography (GC). With the advent of atmospheric pressure ionization, LC-MS has become a routine technique. Recently, the co-occurrence of multiple mycotoxins in the same sample has drawn an increasing amount of attention. Thus, modern analyses must be able to detect and quantitate multiple mycotoxins in a single run. Improvements in tandem MS techniques have been made to achieve this purpose. This review describes the advanced research that has been done regarding mycotoxin determination using hyphenated chromatographic-MS techniques, but is not a full-circle survey of all the literature published on this topic. The present work provides an overview of the various hyphenated chromatographic-MS-based strategies that have been applied to mycotoxin analysis, with a focus on recent developments. The use of chromatographic-MS to measure levels of mycotoxins, including aflatoxins, ochratoxins, patulin, trichothecenes, zearalenone, and fumonisins, is discussed in detail. Both free and masked mycotoxins are included in this review due to different methods of sample preparation. Techniques are described in terms of sample preparation, internal standards, LC/ultra performance LC (UPLC) optimization, and applications and survey. Several future hyphenated MS techniques are discussed as well, including multidimensional chromatography-MS, capillary electrophoresis-MS, and surface plasmon resonance array-MS.

Porcine/chicken or human nephropathy as the result of joint mycotoxins interaction

A survey was made of the literature concerning the occurrence and incidence of mycotoxic nephropathy in pigs and chicks in different countries. Various etiological factors contributing to the development of the disease were considered. The main nephrotoxic fungi as well as the specific conditions for their growth and toxins production were briefly described. A survey was made about the most frequent nephrotoxic fungal contaminants in various feedstuffs from plant origin. In addition, their natural quantities and importance for development of mycotoxic porcine/chick nephropathy (MPN/MCN) are also explored. In addition, a survey was made of the feedstuffs representing the most favorable environment for nephrotoxic fungal growth as well as the most favorable storehouse conditions for this fungal growth were shortly described. The significance of some underestimated fungal species, which can provoke kidney damage, was studied. The importance of joint mycotoxin interaction and newly identified fungal metabolites in the complex etiology of mycotoxic nephropathy ranged in some countries is deeply investigated. The toxicity of the low contamination levels of some combinations of mycotoxins often administered by pigs and chicks in the practice was carefully studied.

Effect ofin vitro digestion on fumonisin B1 in corn flakes

Low levels of fumonisins have been found frequently in corn based breakfast cereals and can occur bound to protein and other matrix components.In vitro digestion of two samples of corn flakes was carried out under "fed conditions." Fumonisins were measured as o-phthaldialdehyde/mercaptoethanol derivatives by LC-fluorescence. One sample of corn flakes (FN12) had high concentrations of fumonisin B1 (FB) (average 125 ng/g) and total bound FB1, (TB FB1) (average 92 ng/g) and the other (FN11) had a low level of free FB1 (average 29 ng/g) and no detectable TB FB1. After incubation of the samples with gastrointestinal tract solutions simulating saliva plus stomach and duodenal juices, chyme was analysed for FB1, hydrolyzed FB1 (HFB1) and partially hydrolyzed fumonisin B1 (PHFB1). The bioaccessibility (percentage of FB1 released from corn flakes into chyme) was 38-78% for incurred FB1 in FN12, 8-54% for incurred plus spiked FB1 in FN12, and 19-66% for incurred plus spiked FB1 in FN11. HFB1 and PHFB1 were not detected. If free FB1 was first extracted from sample FN12, no FB1 was detected in the chyme, indicating no contribution from TB FB1. Concentrations were corrected for method recovery of FB1 or, for bound FB1, partial method recovery of HFB1.

Extracting fumonisins from maize: efficiency of different extraction solvents in multi-mycotoxin analytics

The complete extraction of analytes is of utmost importance when analyzing matrix samples for mycotoxins. Mycotoxins consist of substances with widely different physicochemical properties; therefore, the loss of toxins that occurs in multi-mycotoxin methods due to compromises in the extraction solvent is currently a topic under discussion. With regard to fumonisins, several extractants from recently published multi-mycotoxin methods were investigated when analyzing unprocessed and processed maize matrices. All extractants were tested in a validated on-site method and the extraction yields were compared to those of an HPLC-FLD reference method (EN 14352). Most of the compared multi-mycotoxin methods that have been published were only for analyzing fumonisins in maize or maize-meal; we have applied the extractants of these methods to processed, complex maize matrices for the first time. Our results show that, for extractions with aqueous acetonitrile mixtures with the addition of acid, e.g. MeCN/H2O/acetic acid (79/20/1, v/v/v), higher extraction yields are obtained than with MeCN/H2O (80/20, v/v), in both spiked and naturally contaminated maize matrices. But compared to the results of the reference method EN 14352, the two extractants did not show a similar extraction efficiency. Overall, the extractant MeCN/MeOH/H2O (1/1/2, v/v/v) turned out to be the most appropriate extractant applied in all experiments, obtaining the best and most comparable extraction yields and recoveries. Furthermore, our investigations showed that, with some of the tested extraction solvents, e.g. MeCN/H2O (75/25) containing 50 mmol/l formic acid, stark differences occur when analyzing spiked and naturally contaminated matrices. With spiked matrices, recoveries of approximately 80-110% were obtained, but with naturally contaminated matrices no results comparable to the EN method have been achieved. In contrast, a double extraction with MeCN/H2O/formic acid (80/19,9/0,1, v/v/v), followed by a second polar extraction step with MeCN/H2O/formic acid (20/79,9/0,1, v/v/v), led, for most naturally contaminated samples, to comparable results with the EN method. However, for spiked samples, the same extractant led to raised recoveries of between 120 and 140 %. For some processed matrices, like taco-chips, all tested extractants showed a poor extraction efficiency for fumonisins. By extending the extraction time from 1 to 15 min, a result comparable to that of the reference method could also be obtained for the extractant using MeCN/MeOH/H2O (1/1/2, v/v/v). As this extractant has been used in our recently published method (Trebstein et al. Mycotoxin Res 25:201, 2009), this work also presents an update on this method with respect to the extended extraction time.

Masked mycotoxins: a review

The aim of this review is to give a comprehensive overview of the current knowledge on plant metabolites of mycotoxins, also called masked mycotoxins. Mycotoxins are secondary fungal metabolites, toxic to human and animals. Toxigenic fungi often grow on edible plants, thus contaminating food and feed. Plants, as living organisms, can alter the chemical structure of mycotoxins as part of their defence against xenobiotics. The extractable conjugated or non-extractable bound mycotoxins formed remain present in the plant tissue but are currently neither routinely screened for in food nor regulated by legislation, thus they may be considered masked. Fusarium mycotoxins (deoxynivalenol, zearalenone, fumonisins, nivalenol, fusarenon-X, T-2 toxin, HT-2 toxin, fusaric acid) are prone to metabolisation or binding by plants, but transformation of other mycotoxins by plants (ochratoxin A, patulin, destruxins) has also been described. Toxicological data are scarce, but several studies highlight the potential threat to consumer safety from these substances. In particular, the possible hydrolysis of masked mycotoxins back to their toxic parents during mammalian digestion raises concerns. Dedicated chapters of this article address plant metabolism as well as the occurrence of masked mycotoxins in food, analytical aspects for their determination, toxicology and their impact on stakeholders.

Alkaline cooking (nixtamalisation) and the reduction in the in vivo toxicity of fumonisin-contaminated corn in a rat feeding bioassay

Nixtamalisation is a widely used food processing method in which whole kernel corn is cooked and steeped in alkaline water. It reduces the amount of fumonisin B1 (FB1) that can be detected after cooking. However, the fate of FB1 during nixtamalisation is not fully understood and potentially toxic reaction products, including matrix-associated "masked" FB1 forms that are not detected by routine analytical methods might remain in nixtamalised corn. To assess how nixtamalisation of whole kernel corn affects fumonisin toxicity, male rats were fed diets containing low, mid or high levels of uncooked (LU, MU, HU) or alkaline cooked (LC, MC, HC) FB1-contaminated corn for 3 weeks. The control diet contained uncontaminated corn only. Apoptotic kidney lesions of the type caused by FB1 were not found in the LC or MC groups. Lesions in the group fed HC were minimal and less severe than those found in the rats fed LU, MU or HU. Furthermore, significantly increased sphinganine and sphingosine concentrations indicative of FB1 exposure were found in the kidneys of the rats given LU, MU or HU. Concentrations were also elevated, but to a lesser extent, in rats fed HC, whereas sphinganine and sphingosine concentrations in rats given LC or MC did not differ from the control group. FB1 concentrations in the LC (0.08 mg kg(-1)), MC (0.13 mg kg(-1)) and HC (0.37 mg kg(-1)) diets were markedly reduced compared with their LU (1.8 mg kg(-1)), MU (3.5 mg kg(-1)) and HU (4.2 mg kg(-1)) counterparts as determined by HPLC (n =  1 analysis/diet). Taken together, the findings show that nixtamalisation is an effective cooking method for reducing the potential toxicity of FB1 contaminated corn.

Effects of different extrusion conditions on the chemical and toxicological fate of fumonisin B1 in maize: a short review

Fumonisin B1 (FB1) is a common mycotoxin found in maize and maize-based food products. Although FB1 is relatively heat stable and survives most thermal processes, extrusion cooking has been shown to be effective at reducing levels of the toxin in contaminated maize. This review summarises studies on the chemical and toxicological fate of FB1 in maize extruded under different conditions. Overall, these studies indicate that stability of FB1 depends on the extrusion conditions, e.g. temperature and screw speed, and that the presence of reducing sugars augment apparent loss of the toxin. The chemical fate of FB1 was investigated by measuring FB1, hydrolysed FB1, and N-substituted FB1 compounds with a mass balance approach while the relative toxicity was determined by rat feeding trials. FB1 in contaminated grits was reduced by 21-37% and 77-87% in the absence and presence of 10% (w/w) glucose, respectively, during single-screw extrusion. Greater reductions of 64-72% and 89-94% were achieved by twin-screw extrusion. Mass balance analysis showed that most of the FB1 in grits extruded without glucose was recovered as FB1, whereas the FB1-glucose reaction product, N-(deoxy-D-fructos-1-yl)-fumonisin B1 was the prevalent form after extrusion with glucose. 23 to 38% of FB1 in extruded grits with and without added glucose was bound to component(s) of the maize grits. Only 37-46% of FB1 present in unextruded grits could be recovered as one of the fumonisin species (hydrolysed FB1, N-substituted FB1 compounds) or as matrix-bound forms in extruded grits. Reduced FB1 concentrations in extruded grits and the even lower concentrations in grits extruded with glucose resulted in a dose-dependent reduction of toxicity as shown by the less severe apoptotic lesions and sphingolipid effects that were found in the kidneys of rats. In summary, extrusion processing, especially with glucose supplementation, is potentially useful to reduce FB1 concentrations and toxicity of contaminated maize.

Masked fumonisins in processed food: co-occurrence of hidden and bound forms and their stability under digestive conditions

Fumonisins can occur in foodstuffs as free forms (prent, partially hydrolysed, or totally hydrolysed), as covalently bound fumonisins (bound fumonisins) and as non-covalently bound fumonisins (hidden fumonisins). The formation of several covalently bound fumonisin B1 conjugates upon reaction with sugars and/or amino acids has been reported in the literature so far, but occurrence data are still very poor. Since very little is known about the relevance of both hidden and bound fumonisins in processed products, the present study aimed to evaluate the occurrence of both masked forms in maize-based food products and to study their stability under digestive conditions. The behaviour of covalently bound fumonisin B1 conjugates upon in vitro digestion was evaluated, demonstrating their stability under these conditions. In addition, the co-occurrence of hidden and bound fumonisins in maize-based food products was investigated by application of both alkaline hydrolysis and simulated in vitro digestion assay. The experiments clearly showed that bound fumonisins were rather stable under the applied conditions, whereas hidden fumonisins released their parent forms.