Reduce Mycotoxin Levels Research Articles

Occurrence and Fate Analysis of Mycotoxins in Maize During the Post-Harvest Period

The consumption of agricultural products contaminated with mycotoxins poses a significant threat to the health of both humans and animals. Maize frequently becomes contaminated with toxic fungi while it is still growing in the field. Therefore, more proactive measures should be implemented to reduce mycotoxin levels during the storage and processing of maize after harvest. This article analyzes the prevalent mycotoxins found in maize, specifically aflatoxins, ochratoxins, trichothecenes, fumonisins, and zearalenone. The study provides a comprehensive analysis of the occurrence of mycotoxins in maize during storage, as well as fate analysis of them during processing. It summarizes the impacts of storage time, environmental conditions, storage methods, and agricultural practices on mycotoxin occurrence during storage in the post-harvest period. Furthermore, the different distribution of mycotoxins across various fractions during both dry- and wet-milling processes in the post-harvest processing period is analyzed. Additionally, the strategies to control mycotoxins in maize are also proposed during the post-harvest period. This review offers valuable insights for future research on mycotoxin contamination in maize during the post-harvest period.

Reduction in mycotoxin levels of African nutmeg (Monodora myristica) powder using a high-energy electron beam

This study investigated the role of irradiation with a high-energy electron beam in reducing mycotoxin levels of African nutmeg powder (ANP) samples. African nutmeg was procured from a local market in Accra, Ghana, cleaned, milled, packaged and irradiated using electrons of energy 9 MeV at doses of 2, 4, 6 and 8 kGy. Un-irradiated ANP served as a control. Mycotoxin levels of the treated samples were determined using appropriate standard methods. Aflatoxins B1 (AFB1) and B2 (AFB2) as well as ochratoxin A (OTA) were detected in the nutmeg samples. Irradiation significantly (p < 0.05) reduced mycotoxin levels of the ANP with increasing doses. Aflatoxins G1 and G2 were not detected in any of the samples. A dose of 8 kGy was effective in reducing the mycotoxin levels below the permissible limit in food. This suggests that a high-energy electron beam is effective in reducing mycotoxin levels in African nutmeg powder.

Enhancing bread quality and extending shelf life using dried sourdough

This study investigated the physicochemical properties, microbiological analysis, antifungal activity, and mycotoxin analysis of bread. Eight breads were prepared, including control Bread (CB), control Bread with calcium propionate (CPB), commercial sourdough breads (CCB), control bread made with oven-dried sourdough (SB), and bread baked with oven-dried sourdough fermented by Pediococcus pentosaceus TI6 (SB-TI6). These breads were contaminated with Aspergillus flavus and Penicillium verrucosum, and their shelf life was monitored over 7 days. The results indicated that incorporating sourdough powder into bread significantly extends the shelf life and reduces fungal contamination. This reduction resulted in lower levels of mycotoxins, with the use of dry sourdough fermented by P. pentosaceus TI6 leading to the lowest levels of aflatoxins. In the case of SB-TI6, minor levels of aflatoxin B1 (AFB1), B2 (AFB2), and G1(AFG1) were detected, with only 0.003 mg of AFG2/Kg of the product. Conversely, CB loaves exhibited the highest mycotoxin contamination levels, reaching values of 330 mg of AFB1/Kg. The findings suggested that incorporating dry sourdough in breadmaking served as a viable alternative to synthetic preservatives, effectively reducing mycotoxin levels and enhancing bread safety and shelf life.

Real and statistical processing of barley yield data naturally contaminated with fusariotoxin

Fumonisins are produced by fungi of the genus Fusarium spp., which are widely spread out in the nature. They are produced during grain growth, ripening and harvesting and are known as “field mycotoxins“. Fusarium species can produce compounds that are toxic to animals and humans. In this study, the development of Fusarium toxins was determined in healthy and mechanically damaged barley grains treated and untreated with fungicide, respectively, under natural contamination. It was found that healthy kernels treated with fungicide had the highest yield of 6700 kg.ha-1 followed by the yield of damaged kernels treated with fungicide. The lowest yield of 4850 kg.ha-1 was reported for the damaged and untreated barley grains. The two treatments whose plants were treated with fungicide had a higher yield than their counterparts, i.e. the plants not treated with fungicide. In confirmation of this by mycotoxicological analysis was established the presence of fumonisin 0.234 mg.kg-1 in healthy seeds untreated with fungicide and 0.274 mg.kg-1 in mechanically damaged untreated seeds. Fumonisin concentrations were measured by using Enzyme-Linked Immunosorbent Assay (ELISA) method. The used approach in this study shows that fungicide treatments effectively reduce mycotoxin levels in barley and increase grain yield. The use of fungicides should be combined with other infection mitigation strategies, such as avoiding mechanically damaged grains, which are a suitable substrate for mycotoxins production. These measures will help to improve food and feed safety.

Determination of mycotoxins in nuts, cereals, legumes, and coffee beans and effectiveness of a selenium‐based decontamination treatment

AbstractLiquid chromatography‐tandem mass spectrometry (LC‐MS/MS) was used for the rapid quantification of multiple mycotoxins, specifically aflatoxins B1, B2, G1, and G2 (AFB1, AFB2, AFG1, and AFG2), ochratoxin A (OTA), deoxynivalenol (DON), and zearalenone (ZEN), in walnuts, pistachios, peanuts, coffee beans, rice, and chickpeas from various countries. Total counts of fungi, Aspergillus flavus, and Aspergillus parasiticus were also assessed, along with the effectiveness of a decontamination treatment with inorganic selenium to reduce mycotoxin levels. Of the 78 samples tested, 69% were contaminated with mycotoxins. ZEN, the predominant mycotoxin contaminant, was detected in all the contaminated samples in concentrations often exceeding the maximum level, followed by AFG1 (28% of the contaminated samples), DON (22%), AFG2 (11%), and AFB1 (5.5%). The occurrence of aflatoxins was associated with high proportions of A. flavus and A. parasiticus. Complete removal of AFB1 from walnuts and DON from roasted coffee beans was achieved by treatment with aqueous selenium, while the levels of ZEN and AFG1 were respectively lowered by 65% to 89% depending on the commodity and by about 56% in roasted coffee beans. While this novel treatment is a promising approach for mycotoxin decontamination, it is not intended to replace safe practices upstream.

Effect of Fungicide Treatment on Multi-Mycotoxin Occurrence in French Wheat during a 4-Year Period

Wheat represents one of the most widely consumed cereals worldwide. Cultivated in winter and spring, it is vulnerable to an array of different pathogens, including fungi, which are managed largely through the in-field application of fungicides. During this study, a 4-year field investigation (2018–2021) was performed in France, aiming to assess the efficacy of fungicide treatment to reduce mycotoxin contamination in common and durum wheat. Several different commercially available fungicides were applied via sprayers. Concentrations of mycotoxins and fungal metabolites in wheat were determined using a multi-analyte liquid-chromatography–tandem-mass-spectrometry-based method. The highest contamination levels and strongest effects of fungicides were observed in 2018, followed by 2021. A significant fungicide-mediated reduction was observed for the trichothecenes deoxynivalenol, deoxynivalenol-3-glucoside, nivalenol, and nivalenol-3-glucoside. Furthermore, fungicide treatment also reduced levels of culmorin and its hydroxy metabolites 5- and 15-hydroxy-culmorin, as well as aurofusarin. Interestingly, the Alternaria metabolite infectopyron was increased following fungicide treatment. In conclusion, fungicide treatment was effective in reducing mycotoxin levels in wheat. However, as complete prevention of mycotoxin contamination was not achieved, fungicide treatment should always be combined with other pre- and post-harvest mycotoxin mitigation strategies to improve food and feed safety.

Biocontrol of Fusarium Species Utilizing Indigenous Rooibos and Honeybush Extracts.

Mycotoxins produced by several Fusarium species have a significant effect on reducing maize yield and grain quality and have led to food safety concerns. The antifungal activities of rooibos (Aspalathus linearis) and honeybush (Cyclopia species) tea extracts reduced the growth of plant pathogen Botrytis cinerea, but their efficacy against Fusarium spp. is unknown. In this study, we examined the effects of fermented and unfermented rooibos (A. linearis) and honeybush (Cyclopia subternata) aqueous extracts as well as green tea (Camellia sinensis) against 10 Fusarium species. Conidial viability was assessed by fluorescence microscopy dyes, ATP production was determined using the BacTiter-Glo assay, the mode of action was analyzed by scanning electron microscopy (SEM), and quantification of polyphenols was done using high-performance liquid chromatography with diode array detection (HPLC-DAD). Fermented rooibos extract demonstrated the highest antifungal activity (P < 0.0001) against Fusarium verticillioides MRC 826-E, Fusarium subglutinans MRC 8553, Fusarium proliferatum MRC 8549, and Fusarium globosum MRC 6647, with only 9.53%, 9.26%, 11.0%, and 12.7% ATP production, respectively, followed by antifungal activity of the fermented C. subternata extract against F. subglutinans MRC 8553, F. subglutinans MRC 8554, F. proliferatum MRC 8550, and F. verticillioides MRC 826-E with 3.79%, 6.04%, 6.04%, and 8.40% ATP production, respectively. Extract-treated conidia examined by SEM exhibited disruption of conidial hyphae and collapsed spores. Overall, the fermented rooibos and C. subternata extracts showed higher antifungal activity against the Fusarium species than the unfermented extracts. IMPORTANCE In maize subsistence farming areas in South Africa, daily consumption of maize contaminated by high level of mycotoxins contributes to long-term health effects such as immune deficiency and cancer. Biocontrol methods that are safe and cost-effective are critical to addressing this public health problem. Plant extracts known as biocides or green pesticides are alternatives to chemical pesticides due to their safety and eco-friendly properties. In South Africa, rooibos (Aspalathus linearis) and honeybush (Cyclopia species) contain polyphenols with significant antioxidant and antimicrobial properties. These indigenous herbal teas are widely available and consumed in South Africa and have potential as an innovative approach to reduce mycotoxin levels and, subsequently, human and animal exposure to these toxins. This study evaluates the efficacy of the antifungal activities of several aqueous extracts prepared from fermented and unfermented rooibos (A. linearis), honeybush (Cyclopia subternata), and green tea (Camellia sinensis) on 10 Fusarium strains.

Impact of Combined Processes Involving Ultrasound and Pulsed Electric Fields on ENNs, and OTA Mitigation of an Orange Juice-Milk Based Beverage.

In recent years, several innovative food processing technologies such as ultrasound (USN) and pulsed electric fields (PEF) have emerged in the market, showing a great potential both alone and in combination for the preservation of fresh and processed products. Recently, these technologies have also shown promising applications to reduce mycotoxin levels in food products. Therefore, the objective of this study is to investigate the potential of the combined treatments USN + PEF and PEF + USN on the reduction of Ochratoxin A (OTA) and Enniatins (ENNs) of an orange juice mixed with milk beverage. For this purpose, the beverages were elaborated in the laboratory and individually spiked with mycotoxins at a concentration of 100 µg/L. They were then treated by PEF (30 kV, 500 kJ/Kg) and USN (20 kHz, 100 W, at a maximum power for 30 min). Finally, mycotoxins were extracted using dispersive liquid-liquid microextraction (DLLME), and liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS-IT) was employed to determine them. The results showed promising applications, with reductions up to 50% for OTA and up to 47% for Enniatin B (ENNB) after the PEF + USN treatment combination. Lower reduction rates, up to 37%, were obtained with the USN + PEF combination. In conclusion, the combination of USN and PEF technologies could be a useful tool to reduce mycotoxins in fruit juices mixed with milk.

In vitro detoxification of aflatoxin B1 and ochratoxin A by lactic acid bacteria isolated from Algerian fermented foods

Wheat occupies the first place in Algerian’s diet. However, because of the risk of mycotoxin contamination, its consumption can cause serious health concern to Algerian population. This study aimed to determine the in vitro detoxification properties of lactic acid bacteria (LAB) strains toward aflatoxin B1 (AFB1) and ochratoxin A (OTA), the most prevalent mycotoxins in wheat and derived products in Algeria. Eleven LAB strains isolated from Algerian fermented foods were characterized and identified using API 50 CHL and 16S rDNA sequencing methods. In order to study the ability of LAB strains to remove AFB1 and OTA, viable and heat inactivated cells of two LAB strains (Lab-L4/al and Lab-L1) selected among the eleven isolated and identified ones, as well as of the reference strain Lactobacillus plantarum (LP) R1096 were incubated individually in Citrate Phosphate Buffer (CPB 0.1 M, pH 6 or 5) containing AFB1 and/or OTA at a concentration each of 40 ng/mL for 24 h at 25 °C. Free mycotoxin concentrations were analyzed by HPLC-FLD. The isolated LAB strains were identified as Lactococcus lactis ssp lactis 1, Lactococcus lactis ssp lactis 2 and Lactobacillus paracasei ssp paracasei using API 50 CHL kit, whereas with the molecular method, the strains were identified as Enterococcus faecium and Enterococcus durans. Both viable and nonviable cells of Lab-L4/al and Lab-L1, as well as LP R1096, were able to remove AFB1 and OTA, with efficiency varying between the strains and higher for AFB1 with nonviable cells (>50 %). Removal ability of viable Lab-L4/al and LP R1096 cells increased with a decrease in pH from 6 to 5, while pH had no effect on the amounts of mycotoxins removed by viable Lab-L1 cells. In conclusion, the tested LAB strains were able to reduce the amounts of AFB1 and OTA in vitro conditions. This result suggests that these LAB strains could be used as additives or formative agents to reduce mycotoxin levels in fermented wheat foods such as sourdough bread.

Host Susceptibility of CIMMYT’s International Spring Wheat Lines to Crown and Root Rot Caused by Fusarium culmorum and F. pseudograminearum

The destructive soilborne Fusarium species is one of the most serious challenges facing agriculture. Mycotoxins produced by Fusarium spp. can induce both acute and chronic toxic effects on humans and animals. Massive investments have been made in the last few decades to develop an appropriate management strategy to control Fusarium species in cereals, particularly in wheat, using genetic resistance and other practices, with varied outcomes. The purpose of this research was to find new sources of resistance to both Fusarium culmorum and F. pseudograminearum, which are wheat’s most destructive pathogens in seedlings and adult plants stages. In this study, 26 lines were selected and promoted from a total of 200 spring wheat germplasm received from CIMMYT Mexico plus 6 local check lines. The 32 lines were screened for their resistance reactions to both Fusarium species under different environmental conditions. The discriminant factorial analysis indicated that 7, 12, and 5 were resistant lines against F. culmorum under field, greenhouse, and growth room conditions, respectively. Four lines, L12, L19, L21, and L26, were found to be jointly resistant at the adult and seedling stages in the field and greenhouse. On the other hand, only moderately resistant lines were found for F. pseudograminearum but not completely resistant, which was limited to growth room conditions. Interestingly, five lines (L10, L13, L17, L25, and L28) have shown resistant properties to both Fusarium species. To further evaluate the yield performance of the best-selected 26 lines plus 6 check lines, field trials were conducted under ± F. culmorum inoculum. The highest yield values were obtained from three check lines, as well as the L26, which showed consistency in its reaction to F. culmorum under both field and greenhouse conditions, and produced a high yield (5342 kg/ha). Based on the result obtained, L26 showed a high potential to improve wheat yield and resistance to F. culmorum-caused root and crown rot; therefore, it should be used in wheat crossing programs. Having Fusarium-resistant varieties will ultimately reduce crown rot symptoms and increase grain quality by reducing mycotoxin levels.

BCPC Diseases Review 2022 – Changing Challenges and Changing Tools for Integrated Crop Management

John Lucas, Editorial Board Member and Jon West, Rothamsted Research suggested that the threat posed by Fusarium is likely to increase due to a number of factors including maize crops extending further northwards. The second presentation, given by Derek Croucher, focused on the impact of mycotoxins on producers. The main processor focus on mycotoxins both in the field and during storage is compliance with current legislation, including the ability to test effectively and analyse samples, as well as mitigation measures. There are parallels with legislation of plant protection products, and concerns about potential changes due to exit from the EU. To date these have not occurred, but there is the possibility of GB adoption of EU rules by retailers to facilitate trade. The Food Standards Agency have a priority list of contaminants with maximum limits for mycotoxins in particular foodstuffs, exemplified by current permitted levels for T-2/HT-2 toxins in unprocessed and milled oats. The primary problem in UK oats is Fusarium langsethiae, which causes a mainly symptomless disease, varying in incidence from year to year, with some "high" years, especially in Scotland. There are no commercially viable field mitigation measures. Milling reduces contamination, but this varies and is not batch to batch predictable. There is no reliable rapid test for toxin contamination in oats, and testing by LC-MS/MS is expensive and takes time. In severe years, around 10 – 30% of unprocessed oats would be non-compliant, and as much as 20% of processed products. Identification of compliant versus non-compliant products is challenging and poses a significant risk of recall and reputational damage. The 2022 Diseases review was held at the NIAB Park Farm, Cambridge on October 19th 2022 with a mix of in person and online delegates. The meeting was chaired by Jenna Watts, Head of Plant Health and IPM at the Agriculture and Horticulture Development Board (AHDB). She outlined the current issues and challenges for crop production including climate change, the evolution of pathogen populations to overcome host resistance and pesticides, alterations in the regulatory framework, and changing consumer priorities. New tools are available for disease diagnosis and control, but how can they be most effectively used for integrated crop management? The first two presentations dealt with the issue of mycotoxin contamination of small grain cereals. Professor Simon Edwards (Harper Adams University College) described the various mycotoxins in cereal crops infected by different Fusarium species causing the head blight complex. On wheat the main problems are deoxynivalenol (DON) and zearalenone (ZON) produced by F. graminearum and F. culmorum, while HT-2 and T-2 toxins produced by F. langsethiae and F. sporothrichioides are more of an issue in oats. Mycotoxin profiles vary by cereal, region and season, and exceed permitted regulatory limits in some crops and years. Risk factors for head blight are well known and include crop debris (the main source of inoculum), a warm spring, and heavy rainfall with high humidity in summer. In experimental trials, agronomy accounts for relatively little of the variation in mycotoxin levels. Maize as the previous crop is a major risk factor, along with min tillage and direct drilling. Ploughing or chopping and mixing of debris reduce mycotoxin levels in the crop. There is limited current varietal variation in resistance to head blight. Some fungicides including prothioconazole, metconazole and tebuconazole applied at T3 can reduce DON levels, while Adepidyn (pydiflumetofen) a new but not yet registered SDHI shows some promise for head blight control and toxin reduction. Integrated management to minimize Fusarium mycotoxins in milling wheat therefore combines the use of less susceptible varieties, avoiding high risk crops such as maize in rotations, intense cultivation if a high-risk previous crop has been grown, application of an effective fungicide (or mixture) at T2 and especially T3, and ensuring a timely harvest as late harvesting is associated with higher mycotoxin levels. It was noted that these recommendations are not easy to reconcile with some crop management trends such as reducing cultivations. Professor Edwards also presented some data on HT-2 and T-2 occurrence in oats, and tactics for reducing risk such as switching to spring varieties, or taller more Fusarium resistant varieties, long rotations, and the use of cultivations. Climate change models suggest that the threat posed by Fusarium is likely to increase due to a number of factors including maize crops extending further northwards,

Impact of nonthermal food processing techniques on mycotoxins and their producing fungi

AbstractMycotoxins are a significant threat to food safety and quality. Over the years, mycotoxins have been detected in almost all food and feed crops without any regional barrier. Conventional techniques for decontamination of mycotoxin involve physical, chemical, and biological methods, but these technologies often impact the quality of food in terms of changes in nutritional and sensory attributes. We examined the effects of nonthermal techniques on mycotoxins and their producing fungi to remove or reduce mycotoxin levels in food products without compromising food quality. Nonthermal technologies employ different lethal agents (including ozone, cold plasma, light, pressure, radiation, ultrasound, electric field, and magnetic field) to degrade mycotoxins while minimising product thermal exposure. However, the degradation pathway and toxicology of treated products need further research for a better understanding. With such food process development and optimisation efforts, food processors can employ various nonthermal technologies as tools for delivering consumer‐desired mycotoxin‐free food products with intact nutritional and sensory quality.

Influence of processing steps on the fate of ochratoxin A, patulin, and alternariol during production of cloudy and clear apple juices

Mycotoxins are frequently found in fruits and fruit juices. However, data about occurrence and fate of mycotoxins along the fruit juice processing chain are currently insufficient. Herein, a liquid chromatographic/tandem mass spectrometric (LC–MS/MS) multi-mycotoxin method was developed and applied to investigate the effect of technological unit operations on the fate of three of the most relevant mycotoxins along the processing chain for cloudy and clear apple juice, namely patulin (PAT), ochratoxin A (OTA), and alternariol (AOH). Raw juice obtained directly after dejuicing was spiked with the aforementioned mycotoxins at pilot-plant scale prior to subjecting it to different technological unit operations. Regarding clear apple juice production treatment with a pectinolytic enzyme preparation, and pasteurization were insignificant for mycotoxin reduction, but fining with subsequent filtration was effective, although the mycotoxins showed different affinity towards the tested agents. The most effective fining agent was activated charcoal/bentonite in combination with ultrafiltration, which removed OTA (54 µg/L) and AOH (79 µg/L) to not quantifiable amounts (limit of quantification (LOQ) 1.4 and 4.6 µg/L, respectively), while PAT was reduced only by 20% (from 396 to 318 µg/L). Regarding cloudy apple juice production, all studied processing steps such as centrifugation and pasteurization were ineffective in reducing mycotoxin levels. In brief, none of the common steps of clear and cloudy apple juice production represented a fully effective safety step for minimizing or even eliminating common mycotoxins. Thus, ensuring the sole use of sound apples should be of utmost importance for processors, particularly for those manufacturing cloudy juices.

Low-cost grain sorting technologies to reduce mycotoxin contamination in maize and groundnut

The widespread contamination of foods by mycotoxins continues to be a public health hazard in sub-Saharan Africa, with maize and groundnut being major sources of contamination. This study was undertaken to assess the hypothesis that grain sorting can be used to reduce mycotoxin contamination in grain lots by removing toxic kernels. We tested a set of sorting principles and methods for reducing mycotoxin levels in maize and groundnut from a variety of genotypes and environments. We found that kernel bulk density (KBD) and 100-kernel weight (HKW) were associated with the levels of aflatoxins (AF) and fumonisins (FUM) in maize grain. A low-cost sorter prototype (the ‘DropSort’ device) that separated maize grain based on KBD and HKW was more effective in reducing FUM than AF. We then evaluated the effectiveness of DropSorting when combined with either size or visual sorting. Size sorting followed by DropSorting was the fastest method for reducing FUM to under 2 ppm, but was not effective in reducing AF levels in maize grain to under 20 ppb, especially for heavily AF-contaminated grain. Analysis of individual kernels showed that high -AF maize kernels had lower weight, volume, density, length, and width and higher sphericity than those with low AF. Single kernel weight was the most significant predictor of AF concentration. The DropSort excluded kernels with lower single kernel weight, volume, width, depth, and sphericity. We also found that visual sorting and bright greenish-yellow fluorescence sorting of maize single kernels were successful in separating kernels based on AF levels. For groundnut, the DropSort grouped grain based on HKW and did not significantly reduce AF concentrations, whereas size sorting and visual sorting were much more effective.

Reduction of ochratoxin A in oats and rice by twin-screw extrusion processing with baking soda

Ochratoxin A (OTA) is one of the most important mycotoxins due to its widespread occurrence and toxicity, including nephrotoxicity and potential carcinogenicity to humans. OTA has been detected in a wide range of agricultural commodities and their processed products such as infant cereals and breakfast cereals. Extrusion processing, which is widely used in the manufacture of infant and breakfast cereals, may reduce mycotoxin levels to varying degrees. Hence, the effects of extrusion cooking process on the stability of OTA in spiked (100 μg/kg) oat flakes and rice flour was investigated by using a laboratory-scaled twin-screw extruder. In addition, the effect of twin-screw extrusion and addition of baking soda (0, 0.5, and 1.0% weight of total solids) on the reduction of OTA in oats and rice was investigated. The reductions of OTA in the artificially contaminated oat flakes upon extrusion cooking were in the range of 40–43% whereas the reductions in rice flour ranged from 78 to 82%. The reductions of OTA during extrusion with added baking soda were up to 65% and 72% in oats and rice, respectively. These results suggest that OTA in rice and oats may be reduced significantly by extrusion cooking process, which can be applied to commercial production of infant cereals and breakfast cereals. In addition, baking soda may also help to reduce OTA levels in oats during thermal processing.

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.

Impact of food processing and detoxification treatments on mycotoxin contamination.

Mycotoxins are fungal metabolites commonly occurring in food, which pose a health risk to the consumer. Maximum levels for major mycotoxins allowed in food have been established worldwide. Good agricultural practices, plant disease management, and adequate storage conditions limit mycotoxin levels in the food chain yet do not eliminate mycotoxins completely. Food processing can further reduce mycotoxin levels by physical removal and decontamination by chemical or enzymatic transformation of mycotoxins into less toxic products. Physical removal of mycotoxins is very efficient: manual sorting of grains, nuts, and fruits by farmers as well as automatic sorting by the industry significantly lowers the mean mycotoxin content. Further processing such as milling, steeping, and extrusion can also reduce mycotoxin content. Mycotoxins can be detoxified chemically by reacting with food components and technical aids; these reactions are facilitated by high temperature and alkaline or acidic conditions. Detoxification of mycotoxins can also be achieved enzymatically. Some enzymes able to transform mycotoxins naturally occur in food commodities or are produced during fermentation but more efficient detoxification can be achieved by deliberate introduction of purified enzymes. We recommend integrating evaluation of processing technologies for their impact on mycotoxins into risk management. Processing steps proven to mitigate mycotoxin contamination should be used whenever necessary. Development of detoxification technologies for high-risk commodities should be a priority for research. While physical techniques currently offer the most efficient post-harvest reduction of mycotoxin content in food, biotechnology possesses the largest potential for future developments.

Structure-based virtual screening of hypothetical inhibitors of the enzyme longiborneol synthase-a potential target to reduce Fusarium head blight disease.

Fusarium head blight (FHB) is one of the most destructive diseases of wheat and other cereals worldwide. During infection, the Fusarium fungi produce mycotoxins that represent a high risk to human and animal health. Developing small-molecule inhibitors to specifically reduce mycotoxin levels would be highly beneficial since current treatments unspecifically target the Fusarium pathogen. Culmorin possesses a well-known important synergistically virulence role among mycotoxins, and longiborneol synthase appears to be a key enzyme for its synthesis, thus making longiborneol synthase a particularly interesting target. This study aims to discover potent and less toxic agrochemicals against FHB. These compounds would hamper culmorin synthesis by inhibiting longiborneol synthase. In order to select starting molecules for further investigation, we have conducted a structure-based virtual screening investigation. A longiborneol synthase structural model is first built using homology modeling, followed by molecular dynamics simulations that provided the required input for a protein-ligand ensemble docking procedure. From this strategy, the three most interesting compounds (hits) were selected among the 25 top-ranked docked compounds from a library of 15,000 drug-like compounds. These putative inhibitors of longiborneol synthase provide a sound starting point for further studies involving molecular modeling coupled to biochemical experiments. This process could eventually lead to the development of novel approaches to reduce mycotoxin contamination in harvested grain.

The impact ofBacillus thuringiensis technology on the occurrence of fumonisins and other mycotoxins in maize

In many developing countries, maize is both a staple food crop and a widely-used animal feed. However, adventitious colonisation or damage caused by insect pests allows fungi to penetrate the vegetative parts of the plant and the kernels, the latter resulting in mycotoxin contamination. Maize seeds contaminated with fumonisins and other mycotoxins pose a serious threat to both humans and livestock. However, numerous studies have reported a significant reduction in pest damage, disease symptoms and fumonisin levels in maize hybrids expressing theBacillus thuringiensis (Bt) genecry1Ab, particularly in areas where the European corn borer is prevalent. When other pests are also present, thecry1Ab gene alone offers insufficient protection, and combinations of insecticidal genes are required to reduce damage to plants caused by insects. The combination of Cry1Ab protein with other Cry proteins (such as Cry1F) or Vip proteins has reduced the incidence of pests and, indirectly, mycotoxin levels. Maize hybrids expressing multiple Bt genes, such as SmartStax®, are less susceptible to damage by insects, but mycotoxin levels are not routinely and consistently compared in these crops. Bt maize has a greater economic impact onFusarium toxins than aflatoxins. The main factors that determine the effectiveness of Bt hybrids are the type of pest and the environmental conditions, but the different fungal infection pathways must also be considered. An alternative strategy to reduce mycotoxin levels in crops is the development of transgenic plants expressing genes that protect against fungal infection or reduce mycotoxin levels byin situ detoxification. In this review article, we summarise what is known about the relationship between the cultivation of Bt maize hybrids and contamination levels with different types of mycotoxins.

Plant lignans inhibit growth and trichothecene biosynthesis in Fusarium graminearum

Lignans are a group of diphenolic compounds with anticancer and antioxidant properties which are present in various grains, although their effect on toxigenic fungi has been poorly examined to date. In this study, the impact of the plant lignans pinoresinol and secoisolariciresinol on growth and trichothecene biosynthesis by five Fusarium graminearum strains of different chemotypes was examined in vitro. Both tested lignans exhibited radial growth inhibition against the fungal strains. RT-qPCR analyses of tri4, tri5 and tri11 genes encoding the first steps of the trichothecene biosynthesis pathway revealed a decrease in tri mRNA levels in lignan-treated fungal cultures. Correspondingly, decreased accumulation of toxins in lignan-treated cultures was confirmed by GC-MS analysis. This is the first study to demonstrate the inhibitory effect of both pinoresinol and secoisolariciresinol on growth and trichothecene biosynthesis in F.graminearum. Knowledge of the regulation of trichothecene production in Fusarium graminearum by environmental cues is key to the design of novel strategies to reduce mycotoxin levels in grains. Here, we show that the lignans pinoresinol and secoisolariciresinol, which occur in wheat grains, inhibit radial growth and decrease trichothecene levels in five F.graminearum strains. RT-qPCR analysis reveals that the reduction in trichothecene level in lignan-treated fungal cultures is associated with decreased mRNA transcript levels for the tri4, tri5 and tri11 genes that are involved in the trichothecene biosynthesis pathway.