Thermostability of Fumonisin B(1), a Mycotoxin from Fusarium moniliforme, in Corn

Effect of Popcorn (Zea mays var. everta) Popping Mode (Microwave, Hot Oil, and Hot Air) on Fumonisins and Deoxynivalenol Contamination Levels

Mycotoxins are secondary metabolites that are produced by molds during their development. According to fungal physiological particularities, mycotoxins can contaminate crops before harvest or during storage. Among toxins that represent a real public health issue, those produced by Fusarium genus in cereals before harvest are of great importance since they are the most frequent in European productions. Among them, deoxynivalenol (DON) and fumonisins (FUM) frequently contaminate maize. In recent years, numerous studies have investigated whether food processing techniques can be exploited to reduce the levels of these two mycotoxins, which would allow the identification and quantification of parameters affecting mycotoxin stability. The particularity of the popcorn process is that it associates heat treatment with a particular physical phenomenon (i.e., expansion). Three methods exist to implement the popcorn transformation process: hot air, hot oil, and microwaves, all of which are tested in this study. The results show that all popping modes significantly reduce FUM contents in both Mushroom and Butterfly types of popcorn. The mean initial contamination of 1351 µg/kg was reduced by 91% on average after popping. For DON, the reduction was less important despite a lower initial contamination than for FUM (560 µg/kg). Only the hot oil popping for the Mushroom type significantly reduced the contamination up to 78% compared to unpopped controls. Hot oil popping appears to provide the most important reduction for the two considered mycotoxins for both types of popcorn (−98% and −58% average reduction for FUM and DON, respectively).

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.

Preparative isolation and purification of B-type fumonisins by using macroporous resin column and high-speed countercurrent chromatography

B-type fumonisins (FBs) are water-soluble mycotoxins produced by Fusarium species, which are mainly found in maize products and threaten food safety. Toxicological studies and quantitative determinations of fumonisins require large amounts of pure toxins, and their high prices limit progress in FBs research. In this study, we used a macroporous resin column combined with high-speed countercurrent chromatography to separate large quantities of FBs. A fermented rice culture was extracted with 75% methanol. The dynamic adsorption capacity of FBs on XAD-2 resin was 27.5 mg/g resin at 25°C, pH 4.0, and then the FBs were desorbed with 60% methanol. The crude FBs were further purified using a biphasic system consisting of n-heptane/n-butanol/methanol/water (2:4:1:4, v/v/v/v). The method yielded 1.55 g of FB1 and 0.55 g of FB3 with purities of 96.8% and 95.6%, respectively, from 1 kg of rice culture, and the final overall yield of FBs was 74.8%.

A survey of the mycobiota associated with larvae of the black soldier fly (Hermetia illucens) reared for feed production

Feed security, feed quality and issues surrounding the safety of raw materials are always of interest to all livestock farmers, feed manufacturers and competent authorities. These concerns are even more important when alternative feed ingredients, new product developments and innovative feeding trends, like insect-meals, are considered. The black soldier fly (Hermetia illucens) is considered a good candidate to be used as feed ingredient for aquaculture and other farm animals, mainly as an alternative protein source. Data on transfer of contaminants from different substrates to the insects, as well as the possible occurrence of toxin-producing fungi in the gut of non-processed insects are very limited. Accordingly, we investigated the impact of the substrate/diet on the intestinal mycobiota of H. illucens larvae using culture-dependent approaches (microbiological analyses, molecular identification through the typing of isolates and the sequencing of the 26S rRNA D1/D2 domain) and amplicon-based next-generation sequencing (454 pyrosequencing). We fed five groups of H. illucens larvae at the third growing stage on two substrates: chicken feed and/or vegetable waste, provided at different timings. The obtained results indicated that Pichia was the most abundant genus associated with the larvae fed on vegetable waste, whereas Trichosporon, Rhodotorula and Geotrichum were the most abundant genera in the larvae fed on chicken feed only. Differences in the fungal communities were highlighted, suggesting that the type of substrate selects diverse yeast and mold genera, in particular vegetable waste is associated with a greater diversity of fungal species compared to chicken feed only. A further confirmation of the significant influence of diet on the mycobiota is the fact that no operational taxonomic unit common to all groups of larvae was detected. Finally, the killer phenotype of isolated yeasts was tested, showing the inhibitory activity of just one species against sensitive strains, out of the 11 tested species.

Extrusion and Extruded Products: Changes in Quality Attributes as Affected by Extrusion Process Parameters: A Review

Extrusion of foods is an emerging technology for the food industries to process and market a large number of products of varying size, shape, texture, and taste. Extrusion cooking technology has led to production of wide variety of products like pasta, breakfast cereals, bread crumbs, biscuits, crackers, croutons, baby foods, snack foods, confectionery items, chewing gum, texturized vegetable protein (TVP), modified starch, pet foods, dried soups, dry beverage mixes etc. The functional properties of extruded foods plays an important role for their acceptability which include water absorption, water solubility, oil absorption indexes, expansion index, bulk density and viscosity of the dough. The aim of this review is to give the detailed outlines about the potential of extrusion technology in development of different types of products and the role of extrusion-operating conditions and their effect on product development resulting in quality changes i.e physical, chemical, and nutritional, experienced during the extrusion process.

Tools for Defusing a Major Global Food and Feed Safety Risk: Nonbiological Postharvest Procedures To Decontaminate Mycotoxins in Foods and Feeds

Mycotoxin contamination of foods and animal feeds is a worldwide problem for human and animal health. Controlling mycotoxin contamination has drawn the attention of scientists and other food and feed stakeholders all over the world. Despite best efforts targeting field and storage preventive measures, environmental conditions can still lead to mycotoxin contamination. This raises a need for developing decontamination methods to inactivate or remove the toxins from contaminated products. At present, decontamination methods applied include an array of both biological and nonbiological methods. The targeted use of nonbiological methods spans from the latter half of last century, when ammoniation and ozonation were first used to inactivate mycotoxins in animal feeds, to the novel techniques being developed today such as photosensitization. Effectiveness and drawbacks of different nonbiological methods have been reported in the literature, and this review examines the utility of these methods in addressing food safety. Particular consideration is given to the application of such methods in the developing world, where mycotoxin contamination is a serious food safety issue in staple crops such as maize and rice.

Resistance in Maize Inbred Lines to Fusarium verticillioides and Fumonisin Accumulation in South Africa

Fusarium ear rot of maize, caused by Fusarium verticillioides, is an important disease affecting maize production worldwide. Apart from reducing yield and grain quality, F. verticillioides produces fumonisins which have been associated with mycotoxicoses of animals and humans. Currently, no maize breeding lines are known with resistance to F. verticillioides in South Africa. The objective of this study, therefore, was to evaluate 24 genetically diverse maize inbred lines as potential sources of resistance to Fusarium ear rot and fumonisin accumulation in field trials at Potchefstroom and Vaalharts in South Africa. After artificial silk channel inoculation with F. verticillioides, Fusarium ear rot development was determined at harvest and fumonisins B₁, B₂, and B₃ quantified. A significant inbred line by location effect was observed for Fusarium ear rot severity (P ≤ 0.001), although certain lines proved to be consistently resistant across both locations. The individual inbred lines also differed considerably in fumonisin accumulation between Potchefstroom and Vaalharts, with differentiation between susceptible and potentially resistant inbred lines only being possible at Vaalharts. A greenhouse inoculation trial was then also performed on a subset of potentially resistant and highly susceptible lines. The inbred lines CML 390, CML 444, CML 182, VO 617Y-2, and RO 549 W consistently showed a low Fusarium ear rot (<5%) incidence at both Potchefstroom and Vaalharts and in the greenhouse. Two of these inbred lines, CML 390 and CML 444, accumulated fumonisin levels <5 mg kg^-1. These lines could potentially act as sources of resistance for use within a maize breeding program.

Fumonisin elimination and prospects for detoxification by enzymatic transformation

A technology to efficiently reduce the concentration of carcinogenic and toxic fumonisins in food and feed would be desirable. This class of mycotoxins is produced by the maize pathogen Fusarium verticillioides and other fungi. Fumonisins are frequently found in maize from the warm growing regions of the world, sometimes in considerable concentrations. Their molecular similarity with sphingolipids enables their binding to mammalian ceramide synthase, and the resulting interference with sphingolipid metabolism. Recently, we reported on a cluster of genes of Sphingopyxis sp. MTA144 which enables this alphaproteobacterium to degrade fumonisins. These and the previously known fumonisin catabolism genes and enzymes from the black yeast Exophiala spinifera and from bacterium ATCC 55552 allow the consideration of prospects for enzymatic detoxification of fumonisins in food and feed. All the known fumonisin catabolism pathways start by hydrolytic release of the two tricarballylic acid side chains, followed by removal of the 2-amino group from the core chain by different enzymatic mechanisms. The potential for application of feed enzymes for fumonisin detoxification in the gastrointestinal tract of animals is discussed, and possible applications in processing of maize for feed or food are also considered. To be able to evaluate the requirement for, and potential of, a new, enzyme-based fumonisin detoxification technology, an overview of the state of the art of fumonisin elimination and the known chemical reactions of fumonisins in processing or decontamination is also given. There is a special focus on the toxicity of hydrolysed fumonisins, because they can be generated from fumonisins both by an established, traditional method of maize processing, nixtamalisation, and by enzymatic biotransformation. As a complement to other approaches, enzymatic degradation of fumonisins to ameliorate the health risk of contaminated maize for animals, and possibly also for humans, seems feasible.

Effects of aflatoxin B(1) and fumonisin B(1) on blood biochemical parameters in broilers

The individual and combined effects of dietary aflatoxin B(1 )(AFB(1)) and fumonisin B(1) (FB(1)) on liver pathology, serum levels of aspartate amino-transferase (AST) and plasma total protein (TP) of broilers were evaluated from 8 to 41 days of age. Dietary treatments included a 3 × 3 factorial arrangement with three levels of AFB(1 )(0, 50 and 200 μg AFB(1)/kg), and three levels of FB(1 )(0, 50 and 200 mg FB(1)/kg). At 33 days post feeding, with the exception of birds fed 50 mg FB(1 )only, concentrations of AST were higher (p < 0.05) in all other treatment groups when compared with controls. Plasma TP was lower (p < 0.05) at six days post feeding in groups fed 200 μg AFB(1)/kg alone or in combination with FB(1). At day 33 days post feeding, with the exception of birds fed the highest combination of AFB(1 )and FB(1 )which had higher plasma TP than control birds(, )plasma TP of birds fed other dietary treatments were similar to controls. Broilers receiving the highest levels of AFB(1) and FB(1) had bile duct proliferation and trabecular disorder in liver samples. AFB(1) singly or in combination with FB at the levels studied, caused liver damage and an increase in serum levels of AST.

Co-occurrence of Aflatoxins, Ochratoxin A, Fumonisins, and Zearalenone in Cereals and Feed, Determined by Competitive Direct Enzyme-Linked Immunosorbent Assay and Thin-Layer Chromatography

Aspergillus, Penicillium, andFusariumspecies frequently contaminate crops. For this reason mycotoxins such as aflatoxins (AFs), ochratoxin A (OTA), fumonisins (FBs), and zearalenone (ZEA) are found in food and feed in a wide range of concentrations, depending on environmental and storage conditions. Consumption of mycotoxin-contaminated food and feed has been associated with acute and chronic poisoning and carcinoma. The aim of this study was to determine the incidence and co-occurrence of AFs (B1+B2+G1+G2), OTA, FBs (B1+B2+B3), and ZEA in 37 samples of cereals and feed randomly collected in 2007 from households of an endemic nephropathy (EN) area in Croatia. The mycotoxins were determined using the competitive direct ELISA test (CD-ELISA) in combination with thin-layer chromatography (TLC). The most frequent mycotoxin was ZEA (92%, mean 318.3 μg kg-1), followed by FBs (27%, 3690 μg kg-1), AFs (24.3%, 4.6 μg kg-1), and OTA (16.2%, 9.8 μg kg-1). Levels of AFs, ZEA, and FBs detected by CD-ELISA significantly correlated with the TLC results. However, only one OTA-positive sample was confirmed by TLC due to its high limit of detection. The levels of these mycotoxins were below the permissible limit for animal feed. Twenty-nine percent of cereals were contaminated with FBs, OTA, or ZEA in mass fractions above the permissible limit for humans. Co-occurrence of two toxins varied between 4.2% and 54% and of three between 4.2% and 7.6%. Prolonged co-exposure to AFs, OTA, FBs, and ZEA might increase the risk of various chronic diseases.

Reduction in fusarium toxin levels in corn silage with low dry matter and storage time

Under unfavorable climatic conditions, Fusarium spp. can contaminate corn plants in the field and produce toxins that are present at the time of ensiling. The stability of deoxynivalenol, fumonisins B1 and B2, and zearalenone in corn silage was tested over two consecutive years. Variables studied were corn dry matter (DM) and storage length and temperature. The concentration of all Fusarium toxins decreased upon ensiling ( P < 0.001). Increasing the length of storage and ensiling with low DM resulted in a higher rate of toxin disappearance, particularly for the water soluble toxins deoxynivalenol and fumonisin B1. Toxin disappearance ranged from 50% for zearalenone to 100% for deoxynivalenol. In contrast, temperature did not have any effect on stability ( P > 0.05). These results indicate that low DM at ensiling as well as a prolonged storage could be a practical way to reduce or eliminate some Fusarium toxins in contaminated silages.

Fate of mycotoxins in cereals during extrusion cooking: a review

Extrusion cooking is one of the fastest growing food-processing operations in recent years due to several advantages over traditional methods. Apart from its main goal of improving the quality of intermediate and final processed products, it may incidentally also improve safety because of the potential to reduce mycotoxin levels in cereals. This review is focused on extrusion cooking and aims to give a general overview of its impact in reducing mycotoxin levels in cereals. Extrusion cooking generally decreases the mycotoxins levels at rates depending on different factors such as the type of extruder, the type of screw, the die configuration, the initial mycotoxin concentration, the barrel temperature, the screw speed, the moisture content of the raw material and the use of additives. Reductions of 100, 95 and 83% for fumonisins, aflatoxins and zearalenone, respectively, have been reported during extrusion cooking of cereals, while lower reductions were observed for deoxynivalenol, ochratoxin A and moniliformin, where maximum reductions did not exceed 55, 40 and 30%, respectively.

EFEITOS DA AFLATOXINA B 1 E FUMONISINA B1 SOBRE OS NÍVEIS SÉRICOS DE ASPARTATO AMINO-TRANSFERASE E PROTEÍNA TOTAL DE FRANGOS DE CORTE

RESUMO O objetivo do presente trabalho foi avaliar os efeitos da aflatoxina B 1 (AFB1) e da fumonisina B1 (FB1) sobre os níveis séricos da enzima aspartato amino-transferase (AST) e de proteínas totais de frangos de corte alimentados com ração contendo as toxinas isoladas e em associação, nos níveis de 0, 50 e 200 ?g de AFB1/kg e 0, 50 e 200 mg de FB1/kg. O delineamento experimental foi o inteiramente casualizado em esquema fatorial 3 x 3, com 9 tratamentos e 12 repetições, totalizando 108 aves. As aves foram alimentadas com as rações contaminadas a partir do 8 o dia até o 41o dia de idade. Aos 41 dias de idade, houve um aumento (p < 0,05) nos níveis de AST das aves que receberam dietas contendo AFB1 e FB1, com exceção do grupo que recebeu somente 50 ?g de FB1/kg. Este aumento foi maior quanto mais elevados foram os níveis de AFB1, sendo que um efeito tóxico aditivo foi observado nos tratamentos de associação com 50 mg de AFB1/ kg e 50 ou 200 mg de FB1/kg. Aos 28 dias de idade, observou-se uma redução (p < 0,05) na concentração de proteína dos grupos que receberam ração com 200 ?g de AFB1/kg, com ou sem FB1, porém esta redução não foi observada aos 41 dias de idade. Conclui-se que a intoxicação de frangos de corte com AFB1 e FB1, isoladas ou associadas, causa um aumento na concentração sérica de AST e uma redução nos níveis de proteínas totais após 20 dias de exposição contínua através da ração.

Effects of thermal food processing on the chemical structure and toxicity of fumonisin mycotoxins

Fumonisins are Fusarium mycotoxins that occur in corn and corn-based foods. They are toxic to animals and at least one analogue, fumonisin B1, is carcinogenic to rodents. Their effect on human health is unclear, however, fumonisins are considered to be risk factors for cancer and possibly neural tube defects in some heavily exposed populations. It is therefore important to minimize exposures in these populations. Cleaning corn to remove damaged or moldy kernels reduces fumonisins in foods while milling increases their concentration in some and reduces their concentration in other products. Fumonisins are water-soluble and nixtamalization (cooking in alkaline water) lowers the fumonisin content of food products if the cooking liquid is discarded. Baking, frying, and extrusion cooking of corn at high temperatures ( > or = 190 degrees C) also reduces fumonisin concentrations in foods, with the amount of reduction achieved depending on cooking time, temperature, recipe, and other factors. However, the chemical fate of fumonisins in baked, fried, and extruded foods is not well understood and it is not known if the reduced concentrations result from thermal decomposition of fumonisins or from their binding to proteins, sugars or other compounds in food matrices. These possibilities might or might not be beneficial depending upon the bioavailability and inherent toxicity of decomposition products or the degree to which bound fumonisins are released in the gastrointestinal tract. In this review the affects of cooking and processing on the concentration and chemical structure of fumonisins as well as the toxicological consequences of known and likely fumonisin reaction products are discussed.

Determination of the mycotoxin fumonisin B1 in maize by reversed-phase thin-layer chromatography: a collaborative study

A simple and cost-effective method using thin-layer chromatography for the determination of the mycotoxin fumonisin B1 in maize is described. The analytical method consisted of the extraction of ground maize by shaking with methanol/water (75:25) for 60 min and clean-up of the resultant extract by means of strong anion exchange solid-phase extraction. The purified residue, formed by evaporation of the elution solvent, was reacted with fluorescamine and the fumonisin B1-derivative was separated by reversed-phase thin-layer chromatography using a developing solution of methanol/aqueous 4% potassium chloride (70:30). The derivatized FB1 was readily visualized as a greenish-yellow spot under long wavelength ultraviolet light and quantified by visual comparison with a set of similarly derivatized standards in the range 20-300 ng FB1 spotted on plate. Based on visual comparison, levels down to 0.5 mg kg(-1) were successfully estimated. The method was collaboratively studied in 14 laboratories using four duplicate maize meal samples (including a blank) and a spiked sample for determination of recovery. No significant difference was observed between mean FB1 levels by high-performance liquid chromatography or thin-layer chromatography. Based on within-laboratory relative standard deviations of 27.1-41.7% and between-laboratory relative standard deviations of 35.0-63.3%, the method can be considered semiquantitative. The mean recovery achieved by participants at a spiking level of 2.00 mg kg(-1) was 74.5%.

Fumonisin in tortillas produced in small-scale facilities and effect of traditional masa production methods on this mycotoxin

Four small tortilla plants were visited in Cameron County, Texas, where observations were made on their production methods. Samples of liquids and solids were collected at each stage of the nixtamalization process, and the pH was recorded. Samples were analyzed for fumonisin B(1) (FB(1)) using an immunoaffinity column/HPLC method chosen for its sensitivity for FB(1). It was found that production methods were highly variable among the producers visited, with major differences particularly in the amount of lime added and boiling times. As reported by others working in Mexico and Central America, FB(1) was found in some tortillas. This led to studies of the effects of the various recipes and across a greater range of initial FB(1) concentration/damaged corn than has typically been reported. Five initial concentrations of FB(1) were tested using irradiated corn kernels inoculated with Fusarium verticillioides MRC 826 as the source of FB(1). The amount of FB(1) detected in the masa and tortillas decreased as the concentration of Ca(OH)(2) increased, and boiling time had no apparent effect. Unexpectedly, as the initial concentrations were increased in the corn prior to nixtamalization, greater percentage reductions in FB(1) were observed.

Fumonisins in Brazilian corn-based foods for infant consumption

A survey of 196 samples of corn-based infant foods from 13 cities of Sao Paulo State, Brazil, was carried out to investigate the fumonisin contamination in the products. Based on their ingredients, the products were divided into seven groups: infant cereal designated as types A-D, corn meal, corn starch and instant cereal baby food. Although certain infant food samples were free of fumonisin contamination (<20 microg kg(-1); corn starch and infant cereals of type A, B and D), contamination levels in the other products (corn meal, instant corn-based baby food and cereal type C) were of concern, particularly those in corn meal. All samples in these categories contained fumonisins. The mean level for total fumonisins (FB1 + FB2 + FB3) in corn meal was 2242 microg kg(-1) (maximum 8039 microg kg(-1)), in instant corn-based baby food was 437 (maximum 1096) microg kg(-1) and in infant cereal type C was 664 (maximum 1753) microg kg(-1).

Effects of muffin processing on fumonisins from 14C-labeled toxins produced in cultured corn kernels

The persistence of fumonisins during cooking is known to be affected by several factors, including thermal degradation and the presence of various ingredients in corn-based food recipes that can react with the toxin. A method for the production of corn kernels containing 14C-fumonisins was developed. The corn kernels were colonized by Fusarium verticillioides MRC 826 and supplemented with 1,2-14C-sodium acetate. The specific activity of 14C-FB1 produced made the study of its fate in cornmeal muffins possible. The double-extraction acetonitrile-water-methanol/immunoaffinity column/o-phthaldialdehyde high-performance liquid chromatography (HPLC) method was used to determine FB1 levels in cornmeal muffins. Reductions in FB1 levels in muffins spiked with 14C-labeled and unlabeled FB1 (43 and 48%, respectively) were similar, indicating that the extraction method was efficient and consistent with previous reports. However, with the labeled corn kernel material, recovery levels based on the 14C counts for the eluate from an immunoaffinity column were much higher (90%). This finding indicates that some fumonisin-related compounds other than FB1 that were present in the cornmeal were recognized by the antibodies but not by the HPLC method.

Leaching and binding of fumonisins in soil microcosms

Fumonisin B(1) (FB(1)) is a water-soluble mycotoxin produced by Fusarium verticillioides. Our research objectives were to determine the leaching of FB(1) through soils and FB(1) binding in soil. Leachate columns were used to determine the movement of FB(1) through soil. FB(1)-contaminated corn screenings or water extracts containing FB(1) were placed on the surface of soil columns. In 100% sand columns, FB(1) leaching was only slightly retarded, whereas at 50%, 75%, and 100% Cecil sandy loam, approximately 60%, 50%, and 20% of the FB(1) was recovered in the column leachate, respectively. The FB(1) retained on the 100% Cecil sandy loam column was tightly bound. However, approximately 75% of the bound FB(1) was released with 5% formic acid and 5% formic acid/acetonitrile (1:1), indicating that the nature of the interaction was probably ionic. The results suggest that FB(1) is quite stable in soils and, while tightly bound, under certain environmental conditions could be released.

A method for determining fumonisin B1 in corn using immunoaffinity column clean-up and thin layer chromatography/densitometry

A method for determining fumonisin B1 (FB1) in corn was developed and the clean-up optimized in order to give an extract suitable for one-dimensional thin layer chromatographic (TLC) analysis. FB1 was extracted with a solution of methanol:water (80:20, v/v), purified through an immunoaffinity column and separated on a C18 reversed phase TLC plate. The FB1 was visualized with 0.1 mol/l sodium tetraborate, 0.40 mg/ml fluorescamine in acetonitrile and 0.01 mol/l boric acid:acetonitrile (2:3, v/v) for fluorescence detection, and quantified by densitometric analysis. Water, acetonitrile:water (1:1 v/v) and acetonitrile:water (4:1 v/v) were evaluated as TLC solvents for running both standards and samples together with derivatization procedures aimed at improving separation, resolution, sensitivity and linearity. The mean recovery for FB1 for spiked samples was found to be 85% and the linear equation of standard calibration curve by densitometric analysis gave an r2 value higher than 0.99. The maximum coefficient of variation for replicate analysis of spiked samples was 19%. The absolute amount of FB1 standard detectable on a TLC plate was 2 ng, giving a detection limit for the method of 0.1 mg/kg. The method has been shown to be robust in the application of FB1 monitoring in corn (214 samples) collected in different regions of the country. FB1 was detected in 99% of these samples in the range of 0.2 to 6 mg/kg.

Fumonisin contamination of food: progress in development of biomarkers to better assess human health risks

Fumonisins, fungal toxins produced by Fusarium moniliforme, contaminate maize based foods and feeds throughout the world. They cause liver and kidney toxicity in animals in addition to leukoencephalomalacia in horses and pulmonary edema in pigs. Fumonisin B(1) is carcinogenic in rats and mice. Ecological studies have linked consumption of fumonisin contaminated maize with oesophageal cancer in human populations in South Africa and China. This review discusses the potential health risks for people exposed to the fumonisins, and describes how mechanistic studies of toxicity in animal models have allowed the development of putative biomarkers of fumonisin exposure at the individual level. The requirements for an applicable biomarker include sample availability as well as a high specificity and sensitivity for the exposure of interest. Most environmental toxic insults involve complex exposures both to other toxins and to infections; these confounding factors need to be considered in assessing both the validity of the biomarker and the exposure-disease associations. Fumonisins can be detected in the urine of animals in feeding studies but the sensitivity of the current methodology means only highly exposed people could be monitored. Mechanistic studies indicate that ceramide synthase, an enzyme involved in sphingolipid synthesis, is one cellular target for fumonisin toxicity and carcinogenicity, and this disruption to sphingolipid metabolism increases the ratio of two sphingoid precursors, sphinganine and sphingosine. The altered ratio has been observed in tissues, serum and urine for a number of animal models suggesting it as a good candidate marker of fumonisin exposure. Despite development of analytical methods to measure this biomarker there have been no studies to date correlating it to fumonisin intake in people. Given the toxic effects of fumonisins in animals and the widespread human exposure, which has been calculated to reach 440 micrograms kg(-1) body weight day(-1) in a population consuming high quantities (460 g day(-1)) of contaminated maize, then the development of biomarkers and their application in epidemiological studies should be a priority for research on these toxins.

Equine leukoencephalomalacia associated with ingestion of corn contaminated with fumonisin B1

This article describes clinical, etiologic and pathologic diagnosis of an outbreak of equine leukoencephalomalacia. Two samples of the corn consumed by the affected horses contained fumonisin B1 at levels of 46 and 53 µg/g and Fusarium moniliforme, a good in vitro mycotoxin producer.

Effect of processing on Fusarium mycotoxins

Mycotoxins are secondary metabolites produced by a wide variety of fungal species that contaminate food or feed. Fumonisins (FUM), deoxynivalenol (DON) and zearalenone (ZEN) are examples of common mycotoxins in grains that have been shown to affect human and/or animal health. Physical, chemical and biological methods have been used for decontaminating grains containing these toxins. Some treatments reduce the concentration of mycotoxins while others are ineffective. For example, removal of damaged grain by density segregation can reduce DON and ZEN concentrations in corn and wheat. In contrast, thermal processing is usually ineffective for reducing the FUM and ZEN content of foods. More work is needed to identify effective methods for detoxifying mycotoxin contaminated food.

Effect of commercial processing on fumonisin concentrations of maize-based foods

Fumonisin-contaminated maize was used to study the effect of three cooking and food processing methods and residual contamination of the food product. Frying, autoclaving and extrusion were examined with naturally-contaminated maize meal, maize flour and sweet maize kernels, all at two fumonisin concentrations. High Pressure Liquid Chromatography determination of fumonisins B1 and B2 and hydrolized fumonisin B1 (AP1) were performed in unprocessed materials and at the end of the experimental runs. Reductions of fumonisins concentration in processed products were obtained for fried polenta and from one of the two runs of extruded maize batter. These reductions were consistent with previous studies of the thermal degradation of fumonisins. Autoclaving sweet maize kernels apparently resulted in reductions of fumonisin concentrations that were highly temperature dependent, but this needs further study. The unexpectedly large reduction in fumonisin concentrations in the extrusion processing of batter with high initial concentrations also needs further investigation. There was no evidence that AP1 was formed under any of the conditions tested.

Fate of fumonisin B(1) in corn kernel steeping water containing SO(2)

Six 100 ppm fumonisin B(1) (FB(1)) solutions were prepared by dissolving pure standard in six different solvents containing SO(2). Two of the solvents contained 0.2 or 0.4% SO(2) in distilled water. The other four solvents were obtained by steeping corn kernels at 60 degrees C in a 0.2% SO(2) aqueous solution for 6, 12, 24, or 48 h. After the addition of FB(1), all solutions were maintained at 60 degrees C for 7 days. Fumonisin B(1) content in each solution was determined in triplicate by HPLC. Steeping corn kernels in 0.2% solution at 60 degrees C for 6 h seems to be the most effective treatment to decrease the amount of FB(1).

Chromatographic determination of the fumonisin mycotoxins

The fumonisins are a recently identified group of fungal toxins, occurring worldwide in naturally contaminated maize, which have elicited considerable attention over the past decade due to their association with the animal disease syndromes, equine leukoencephalomalacia and porcine pulmonary oedema, and their reported association with oesophageal cancer in rural areas of Transkei, South Africa and Linxian County, China. This paper reviews the development of sensitive chromatographic analytical methods for the determination of these toxins in a range of mainly maize or maize-based food matrices. Initial attempts at gas chromatographic determination of these toxins were supplanted by the successful development of liquid chromatographic methods based on solid-phase extraction (SPE) of solvent extracts, followed by precolumn derivatisation and HPLC determination using fluorescence detection. The most widely used method involves strong anion-exchange (SAX) SPE and the use of o-phthaldialdehyde as derivatising agent. In contrast, the development of thin-layer chromatographic methods enables large numbers of samples to be screened economically. The recent advances in liquid chromatography-mass spectrometry have resulted in the development of suitable methods for fumonisin analysis without the need of derivatisation.

The use of the chicken embryo screening test and brine shrimp (Artemia salina) bioassays to assess the toxicity of fumonisin B1 mycotoxin

Chicken embryos and brine shrimp naulpii were utilized in short-term toxicity bioassays to assess their sensitivity to the mycotoxin fumonisin B1 (FB1). Fertile chicken eggs (Cobb x) were dosed with FB1 on day 2 of incubation by the injection of 100 microliters of aqueous solution into the air space of each egg. Eggs were incubated with mechanical rotation until hatch, at which time mortality was assessed. Probit transformation of the mortality data produced a linear line of best fit (P < 0.05), from which an LD50 of 52 micrograms FB1/egg, equivalent to a concentration of 1.3 microns hatched in artificial seawater and exposed to FB1 in an optimized 96-well plate assay with a 48 hr mortality endpoint. Probit transformation of the mortality data resulted in an LC50 of 1.7 microns FB1, or 1.2 micrograms FB1/ml. Thus, at the cellular level, both bioassays appeared sensitive to FB1; however, from the standpoint of use as a screening assay, the chicken embryo bioassay is limited by the relatively high dose of FB1 required per egg. It is anticipated that the design and simplicity of the brine shrimp bioassay will accommodate screening for FB1 toxicity in contaminated samples.

Approaches to the risk assessment of fumonisins in corn-based foods in Canada

The presence of fumonisins and associated mycotoxins from Fusarium moniliforme in corn-based foods has recently become a concern in North America and elsewhere. Monitoring of various corn based foods and food commodities for fumonisins is ongoing in both the USA and Canada, and the results can be used for preliminary exposure assessments. The role of Fusarium moniliforme and the fumonisins in some diseases of livestock has been established. Considerable information is available on the mechanism of action of the fumonisins. With the availability of increased quantities of pure fumonisins, several subchronic toxicity studies, designed to establish dose response characteristics in rodents have now been completed. However, since concerns about the chronic toxicity of the fumonisins have not yet been adequately addressed, a tolerable daily intake cannot be established at this time. With the information at hand it is, nevertheless, possible to arrive at an interim risk assessment, which can be used to make interim risk management decisions. A total of 361 samples, covering 4 years of a Canadian survey, have been analyzed to date. Of these, 64 contained > or = 0.1 micrograms/g fumonisin B1, and 10 contained > or = 1 microgram/g. The 'all persons' estimate for the intake of fumonisins from these foods was < 0.089 micrograms/kg bw for 5-11 year-old children, and lower for other age groups. Based on an assessment of the available information on the toxicity of fumonisins, it can be concluded that these estimated intakes are unlikely to pose a health risk.

Fumonisins, mycotoxins of increasing importance: their nature and their effects

The fumonisins (FBs) are a group of closely related mycotoxins that are prevalent in maize. They were isolated from strains of Fusarium moniliforme (Sheldon), which were implicated in the aetiology of human oesophageal cancer in the Transkei, South Africa. Their discovery explained the cause of equine encephalomalacia, or "hole in the head" syndrome, when it was found by feeding trials in horses that they elicited the disease. Subsequently, they were found to cause hepatic cancer in rats and pulmonary oedema in pigs, with most animal species tested showing liver and kidney damage. FB1 is the most important of the group and, although poorly absorbed from the gastrointestinal tract, its action is at the cellular level, affecting sphingolipid metabolism. Ceramides derived from sphingosine metabolism are cell regulatory factors affecting, among other things, DNA synthesis. Because FB1 has a close molecular resemblance to sphinganine, it interferes with ceramide biosynthesis and, hence, the processes that it regulates, which is thought to explain its carcinogenic properties. Studies on the FBs are still at a relatively early stage, but it is already clear that they play an important role in animal mycotoxicoses and, by implication, in human disease. A more positive aspect is that they will be used in elucidating the role of sphingolipids in cellular regulation.

Occurrence of fumonisins in the U.S. food supply

Over the past several years a great deal of interest has been shown in assessing human exposure to the fumonisins. This interest, of course, arises as a result of the finding of fumonisins in foods and the expanding data base on toxicological effects, both acute and sub-acute. The basis for exposure assessment lies in surveys of foods as well as a knowledge of consumption patterns. An overview of such surveys, limited as they are, will be presented along with some evaluation of the methodology used.

Effect of thermal processing on the stability of fumonisins

Fumonisins, a group of mycotoxins produced by Fusarium moniliforme in corn, have been implicated in several animal and human diseases. F. moniliforme and the fumonisins are an area of incresing concern for corn producers and consumers. Consequently, there is interest in reducing human and animal exposure to these fungal toxins. Studies of the effects of biological, chemical, and physical treatments on the reduction of fumonisin levels in food have shown variable results. Work was conducted at the U.S. Food and Drug Administration, National Center for Food Safety and Technology, to determine the effects of thermal processing on fumonisins B1 (FB1) and B2 (FB2) in an aqueous buffer. Parameters that were studied included processing time (0-60 min), processing temperature (100-235 degrees C), and buffer pH (4, 7, and 10). The rate and extent of fumonisin decomposition increased with processing temperature. Less than 27% of FB1 and less than 20% of FB2 were lost when processing temperatures were less than or equal to 125 degrees C for 60 min. After 60 min at 150 degrees C, losses of FB1 and FB2 were 80-90% at pH 4, 18-30% at pH 7, and 40-52% at pH 10. At temperatures greater than or equal to 175 degrees C, more than 80% of FB1 and FB2 was lost after 60 min. These results indicate that foods reaching temperatures greater than 150 degrees C during processing may have lower fumonisin levels. More work is needed to quantitate the effects of different processing operations (baking, extrusion, frying) on the fumonisin content of corn-based foods.

Effect of processing on fumonisin content of corn

Fumonisins (FBs) are a family of mycotoxins produced by Fusarium moniliforme and F. proliferatum, predominant corn pathogens, and are found in most corn-containing foods. The FBs are heat stable, resistant to ammoniation, and unlike most mycotoxins, are water-soluble. The levels in corn and corn-containing foods will be presented ranging from < 20 ppb to > 2 ppm. Washing of contaminated FB-corn with water did not reduce the measured FB levels of significantly. The traditional processing step to make tortilla flour, nixtamalization [Ca(OH)2 cooking] to produce masa, reduced FB levels but produced hydrolyzed FB which was almost as toxic as FB. Retorting sweet corn in brine apparently produced hydrolyzed FB. Fermentation of corn to ethanol did not alter FB levels but distillation yielded FB-free ethanol. Attempts to enzymatically modify FB with several enzymes were unsuccessful. Reactions between FB and reducing sugars (glucose or fructose) to produce Schiff's bases yielded products that were not toxic. The effects of these processing treatments must be evaluated both chemically and biologically.

Growth of Fusarium moniliforme and its biosynthesis of fumonisin B1 on maize grain as a function of different water activities

The production of fumonisin by Fusarium moniliforme during its growth on maize depends on extrinsic factors. In particular, experiments on maize grain at different water activities (aw) (1, 0.95, 0.90, 0.85) have demonstrated the influence of aw on fumonisin biosynthesis, and on fungal growth defined by measurement of ergosterol levels. Fumonisin levels dropped threefold when aw was lowered by 5%, but growth rate was unchanged. A 10% reduction in aw from 1 to 0.90 resulted in a 20-fold drop in fungal growth, and fumonisin production was reduced 300-fold. At a threshold aw of 0.85-0.86, F. moniliforme exhibited virtually no measurable metabolic activity, and hence no fumonisin production.

Genetic analysis of fumonisin production and virulence of Gibberella fujikuroi mating population A (Fusarium moniliforme) on maize (Zea mays) seedlings

The phytopathogenic fungus Gibberella fujikuroi mating population A (anamorph, Fusarium moniliforme) produces fumonisins, which are toxic to a wide range of plant and animal species. Previous studies of field strains have identified a genetic locus, designated fum1, that can determine whether fumonisins are produced. To test the relationship between fumonisin production and virulence on maize seedlings, a cross between a fum1+ field strain that had a high degree of virulence and a fum1- field strain that had a low degree of virulence was made, and ascospore progeny were scored for these traits. Although a range of virulence levels was recovered among the progeny, high levels of virulence were associated with production of fumonisins, and highly virulent, fumonisin-nonproducing progeny were not obtained. A survey of field strains did identify a rare fumonisin-nonproducing strain that was quite high in virulence. Also, the addition of purified fumonisin B1 to virulence assays did not replicate all of the seedling blight symptoms obtained with autoclaved culture material containing fumonisin. These results support the hypothesis that fumonisin plays a role in virulence but also indicate that fumonisin production is not necessary or sufficient for virulence on maize seedlings.