Occurrence of modified mycotoxins in Latin America: an up-to-date review

The Latin America region has a considerable extent of varied climate conditions: from tropical, subtropical, and warm temperate to temperate. Among the surface territory, different agricultural products are produced, making them an important food source for human consumption. Fungal species commonly colonize those important agricultural products and often contaminate them with mycotoxins that have a major impact on health, welfare, and productivity. Nowadays, special attention is paid to modified mycotoxins, which are those that cannot be detected by conventional analytical methods. However, little data about their natural occurrence in food and feed is available, especially in Latin American countries, where, among all the countries in this region, only a few of them are working on this subject. Thus, the present review summarizes the published information available in order to determine the possible human exposure risk to these toxins.

Comparison of two commercial methods with a UHPLC-MS/MS method for the determination of multiple mycotoxins in cereals

Immunoassay-based techniques are important on-site screening tools for the detection of mycotoxins in cereals. This study aims to evaluate the trueness, precision, repeatability and cross-reactivity of commercially available test strips, ELISA kits and UHPLC-MS/MS on analyzing zearalenone, ochratoxin A, deoxynivalenol, T-2 toxin and fumonisin B₁. The results showed that false negative rate (25.7 %-37.4 %) of all tested mycotoxins by test strips was higher than the false positive rate (0 %-31.0 %). The repeatability of ELISA kits at the declared LOD dispersed from -85.7 % to +98.4 %. ELISA kits were more accurate at 50 % of the maximum residue limit (MRL) of mycotoxins than 150 % and 200 %. All the tested deoxynivalenol/zearalenone derivatives had cross-reactivity with different level, and sample matrix could reinforce this overestimation of target mycotoxin. This study emphasized that higher-quality antibody screening and more analytical performance investigations are need to address for on-site detection of mycotoxins in the future.

Nanoparticles as a Solution for Eliminating the Risk of Mycotoxins

Mycotoxins are toxic secondary metabolites produced by certain filamentous fungi. The occurrence of mycotoxins in food and feed causes negative health impacts on both humans and animals. Clay binders, yeast cell walls, or antioxidant additives are the most widely used products for mycotoxin elimination to reduce their impact. Although conventional methods are constantly improving, current research trends are looking for innovative solutions. Nanotechnology approaches seem to be a promising, effective, and low-cost way to minimize the health effects of mycotoxins. This review aims to shed light on the critical knowledge gap in mycotoxin elimination by nanotechnology. There are three main strategies: mold inhibition, mycotoxin adsorption, and reducing the toxic effect via nanoparticles. One of the most promising methods is the use of carbon-based nanomaterials. Graphene has been shown to have a huge surface and high binding capacity for mycotoxins. Attention has also been drawn to polymeric nanoparticles; they could substitute adsorbents or enclose any substance, which would improve the health status of the organism. In light of these findings, this review gives new insights into possible future research that might overcome challenges associated with nanotechnology utilization for mycotoxin elimination from agricultural products.

Current challenges in the diagnosis of zearalenone toxicosis as illustrated by a field case of hyperestrogenism in suckling piglets

Background

The mycotoxin zearalenone (ZEN) causes functional and morphological alterations in reproductive organs of pigs. In the field, diagnosis of ZEN-induced disorders is often challenging, as relevant feed lots are no longer available, or feed analysis results are not conclusive. Here, we report a field case of hyperestrogenism in newborn piglets. Surprisingly, more than 50 fungal metabolites were detected in hay pellets fed to gestating sows, including ZEN and its modified form zearalenone-14-sulfate (ZEN-14-S). Despite the broad contamination range in this unconventional feed component, a definite diagnosis of mycotoxicosis could not be achieved. In this context, current limitations regarding the confirmation of suspected cases of ZEN-induced disorders are discussed, covering both feed analysis and the biomarker approach.

Case presentation

A piglet producer with 200 sows experienced a sudden increase in suckling piglet losses up to 30% by lower vitality and crushing. Predominant clinical signs were splay legs and signs of hyperestrogenism such as swollen and reddened vulvae in newborn piglets. The first differential diagnosis was ZEN mycotoxicosis although feed batches had not been changed for months with the exception of ground hay pellets, which had been included in the diet five months before. Analysis of hay pellets resulted in a sum value of ZEN and its modified forms of more than 1000 μg/kg, with ZEN-14-S alone accounting for 530 μg/kg. Considering the inclusion rate of 7% in the diet for gestating sows, the severe impact of the additional ZEN load due to the contaminated hay pellets seemed unrealistic but could not be completely excluded either. One month after hay pellets had been removed from the diet no further clinical signs were observed.

Conclusions

Enrichment materials and other fibre sources can contain significant amounts of mycotoxins and should be therefore included in feed analysis. Adequate methods for broad spectrum mycotoxin determination, including modified mycotoxins, are important. As highlighted by this field case, there is a need to establish reliable biomarkers for ZEN exposure in pigs. Currently, available biomarkers do not allow a solid prediction of the ZEN intake of pigs under field conditions, which limits their application to experimental studies.

Cross-reactivity features of deoxynivalenol (DON)-targeted immunoaffinity columns aiming to achieve simultaneous analysis of DON and major conjugates in cereal samples

Immunoaffinity columns (IACs) are a well-established tool in the determination of regulated mycotoxins in food and feed commodities. However, they also have the potential to become attractive pre-concentration and clean-up materials for the determination of masked (also called modified) mycotoxins, which have been recognised as important contributors to the toxicological hazard deriving from fungal spoilage of goods. However, the information available in the literature concerning the cross-reactivity of DON-IACs against the major conjugates (DON-3-G, 15-AcDON and 3-AcDON) is incomplete and often contradictory. We have carried out a detailed characterisation of the cross-reactivity of the four main IACs brands against DON and its conjugates as well as an assessment of the competition among the analytes. Only one IAC enabled the simultaneous analysis of all relevant DON forms while two missed 15-AcDON and the fourth one missed DON-3-G and 3-AcDON. In the case of the multivalent IAC, the analytes modified at the C-3 position compete for the antibody binding with preference for 3-AcDON (less spatially hindered) while DON-3-G has the more-hindered access to the active sites. Taking into consideration the levels of DON conjugates existing in real samples, the cross-reactivity of one DON-IAC allows a quantitative analysis of all of these analytes. Important but rather neglected aspects such as the continuous supply of IACs with identical characteristics, and of columns which are strictly blank, are also addressed in this paper.

Analytical methods for determination of mycotoxins: An update (2009-2014)

Mycotoxins are a problematic and toxic group of small organic molecules that are produced as secondary metabolites by several fungal species that colonise crops. They lead to contamination at both the field and postharvest stages of food production with a considerable range of foodstuffs affected, from coffee and cereals, to dried fruit and spices. With wide ranging structural diversity of mycotoxins, severe toxic effects caused by these molecules and their high chemical stability the requirement for robust and effective detection methods is clear. This paper builds on our previous review and summarises the most recent advances in this field, in the years 2009-2014 inclusive. This review summarises traditional methods such as chromatographic and immunochemical techniques, as well as newer approaches such as biosensors, and optical techniques which are becoming more prevalent. A section on sampling and sample treatment has been prepared to highlight the importance of this step in the analytical methods. We close with a look at emerging technologies that will bring effective and rapid analysis out of the laboratory and into the field.

Proposal of a comprehensive definition of modified and other forms of mycotoxins including "masked" mycotoxins

As the term “masked mycotoxins” encompasses only conjugated mycotoxins generated by plants and no other possible forms of mycotoxins and their modifications, we hereby propose for all these forms a systematic definition consisting of four hierarchic levels. The highest level differentiates the free and unmodified forms of mycotoxins from those being matrix-associated and from those being modified in their chemical structure. The following lower levels further differentiate, in particular, “modified mycotoxins” into “biologically modified” and “chemically modified” with all variations of metabolites of the former and dividing the latter into “thermally formed” and “non-thermally formed” ones. To harmonize future scientific wording and subsequent legislation, we suggest that the term “modified mycotoxins” should be used in the future and the term “masked mycotoxins” to be kept for the fraction of biologically modified mycotoxins that were conjugated by plants.

Developments in mycotoxin analysis: an update for 2012-2013

This review highlights developments in mycotoxin analysis and sampling over a period between mid-2012 and mid-2013. It covers the major mycotoxins: aflatoxins, Alternaria toxins, ergot alkaloids, fumonisins, ochratoxins, patulin, trichothecenes and zearalenone. A wide range of analytical methods for mycotoxin determination in food and feed were developed last year, in particular immunochemical methods and liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS)-based methods. After a section on sampling and sample preparation, due to the rapid spread and developments in the field of LC-MS/MS multimycotoxin methods, a separate section has been devoted to this area of research. It is followed by a section on mycotoxins in botanicals and spices, before continuing with the format of previous reviews in this series with dedicated sections on method developments for the individual mycotoxins.

Rapid enzymatic hydrolysis of masked deoxynivalenol and zearalenone prior to liquid chromatography mass spectrometry or immunoassay analysis

Recently it has been shown that conjugates (‘masked mycotoxins’) may contribute to the total daily intake of hazardous mycotoxins. Therefore, there is an urgent need for rapid analysis methods that assess the level of both free and masked mycotoxins in food and feed. However, the analysis of masked mycotoxins by either immunoassays or instrumental methods, such as liquid chromatography tandem mass spectrometry (LC-MS/MS), is severely hindered by the lack of standards and the unpredictable cross-reactivity profiles of the available antibodies. In this work, 26 enzymes were explored for rapid hydrolysis of masked mycotoxins using deoxynivalenol-3-glucoside (DON-3G) as model compound. Following initial screening, the most promising enzyme, a fungal 1,3-β-glucanase (laminarinase), was investigated in detail and found to be fit-for-purpose, providing complete conversions in minutes rather than hours according to LC-MS/MS analyses. As a proof of concept, the enzymatic pretreatment was applied to an extract of beer containing DON-3G. In addition, the feasibility of a fully automated enzymatic pretreatment of masked mycotoxin standards in an autosampler was demonstrated in an imaging surface plasmon resonance immunoassay set-up. Such an automated pretreatment was found to be equally applicable to other mycotoxin conjugates, as shown by the conversion of zearalenone-14-β-D-glucopyranoside and zearalenone-14-sulphate, in the latter case using a sulphatase enzyme. It is envisaged that laminarinase could be useful for other masked mycotoxins as well.

Looking for the best compromise in rapid food mycotoxin tests: speed, sensitivity, precision and accuracy

Mycotoxins provide additional challenges to food businesses in terms of successful management of food-safety management systems. These reflect, in part, an unusually high dependency on the activities of others in the supply chain to ensure that levels of contamination remain within set limits. Consequently analyses for mycotoxins by food businesses are primarily commissioned for one or a combination of two reasons: to determine compliance with regulatory or commercial standards or; as part of an exercise to verify the efficacy of the businesses foodsafety management systems. Given the regulatory/commercial implications, the standard of evidence needed to demonstrate (non)compliance will be the greater than that needed for simple verification. Consequently, decisions relating to matters of regulatory or commercial arbitration need to be based on agreed and well defined methods of analysis, which are normally laboratory-based. These data are also often sufficient to be used to verify foodsafety management systems. However, supply conditions may predicate the need for increased levels of verification and rapid mycotoxin test-kits have the potential to both meet this need and satisfy the requirements of statistical process control. Nevertheless, it is important to note that deployment of such test-kits cannot be considered to be a ‘turnkey’ exercise and that, as in the case of laboratory-based assays, care must be taken in the validation and subsequent verification of their use for a given material being used within a food business. In particular, this means demonstrating under local conditions that results from the use of these test-kits are comparable to those that would be obtained using official or reference methods.

Development and evaluation of monoclonal antibodies for the glucoside of T-2 toxin (t2-glc)

The interactions between fungi and plants can yield metabolites that are toxic in animal systems. Certain fungi are known to produce sesquiterpenoid trichothecenes, such as T-2 toxin, that are biotransformed by several mechanisms including glucosylation. The glucosylated forms have been found in grain and are of interest as potential reservoirs of T-2 toxin that are not detected by many analytical methods. Hence the glucosides of trichothecenes are often termed “masked” mycotoxins. The glucoside of T-2 toxin (T2-Glc) was linked to keyhole limpet hemocyanin and used to produce antibodies in mice. Ten monoclonal antibody (Mab)-producing hybridoma cell lines were developed. The Mabs were used in immunoassays to detect T2-Glc and T-2 toxin, with midpoints of inhibition curves (IC₅₀s) in the low ng/mL range. Most of the Mabs demonstrated good cross-reactivity to T-2 toxin, with lower recognition of HT-2 toxin. One of the clones (2-13) was further characterized with in-depth cross-reactivity and solvent tolerance studies. Results suggest Mab 2-13 will be useful for the simultaneous detection of T-2 toxin and T2-Glc.

Electrochemical affinity biosensors for detection of mycotoxins: A review

This review discusses the current state of electrochemical biosensors in the determination of mycotoxins in foods. Mycotoxins are highly toxic secondary metabolites produced by molds. The acute toxicity of these results in serious human and animal health problems, although it has been only since early 1960s when the first studied aflatoxins were found to be carcinogenic. Mycotoxins affect a broad range of agricultural products, most important cereals and cereal-based foods. A majority of countries, mentioning especially the European Union, have established preventive programs to control contamination and strict laws of the permitted levels in foods. Official methods of analysis of mycotoxins normally requires sophisticated instrumentation, e.g. liquid chromatography with fluorescence or mass detectors, combined with extraction procedures for sample preparation. For about sixteen years, the use of simpler and faster analytical procedures based on affinity biosensors has emerged in scientific literature as a very promising alternative, particularly electrochemical (i.e., amperometric, impedance, potentiometric or conductimetric) affinity biosensors due to their simplicity and sensitivity. Typically, electrochemical biosensors for mycotoxins use specific antibodies or aptamers as affinity ligands, although recombinant antibodies, artificial receptors and molecular imprinted polymers show potential utility. This article deals with recent advances in electrochemical affinity biosensors for mycotoxins and covers complete literature from the first reports about sixteen years ago.

Special issue: Masked mycotoxins

In 1990, Gareis et al. referred to a zearalenone-glycoside as a ‘masked mycotoxin’ to emphasise the fact that this mycotoxin conjugate was not detected by routine analysis of food or feed, but probably contributed to the total mycotoxin content and subsequent effects. Indeed, pigs fed with mixed feed, artificially contaminated with synthesised zearalenone-4-ß-D-glucopyranoside, excreted zearalenone (ZEA) and α-zearalenol in their faeces and urine, demonstrating release of the aglucone during digestion. Earlier, in 1988, Engelhardt et al. demonstrated that wheat and maize cell cultures were able to transform ZEA to the ß-D-glucopyranoside-conjugate as part of their plant metabolism. It is generally known that plants can reduce the toxicity of phytotoxic compounds by chemical modification. This plant detoxification process includes the conjugation of mycotoxins to polar substances such as sugars, amino acids and sulphate, and subsequent storage of the conjugates in cell vacuoles. In 2002, Schneweis et al. described the natural occurrence of zearalenone-4-glucoside in wheat, while in 2005, Berthiller et al. published the first report on the natural occurrence of deoxynivalenol-3-glucoside (DON-3G) in maize and wheat samples. Since then, research on masked mycotoxins has grown exponentially. Besides plant metabolism, food technological processes also have an impact on the masking mechanism, specifically in cereal-based products in the case of fumonisins (Humpf and Voss, 2004; Dall’Asta et al., 2008) and deoxynivalenol (DON) (Lancova et al., 2008).