Aflatoxins In Grains Research Articles

Current Strategies in Controlling Aspergillus flavus and Aflatoxins in Grains during Storage: A Review

Aspergillus flavus is a ubiquitous pathogen that can infect many foods and grains, and it produces large amounts of aflatoxins during their storage. Aflatoxins are considered highly toxic and carcinogenic to humans, and they cause great damage to crop production, food security, and human health. Thus, controlling A. flavus and aflatoxins in grains presents a great challenge to humans worldwide. Over the past decade, many strategies have been demonstrated to be useful in controlling A. flavus and aflatoxins during food storage. These methods involve physical agents, chemical agents, biological agents, etc. Some of these methods are currently used in actual production. In this review, we summarize the reported methods for controlling A. flavus and aflatoxins during food storage in the past ten years and elucidate their advantages and disadvantages. The methods discussed include irradiation technology; low oxygen atmospheres; chemical fungicides (benzalkonium chloride, iodine, ammonium bicarbonate, and phenolic and azole compounds); biological agents from plants, animals, and micro-organisms; and aflatoxin elimination methods. We expect that this review will promote the applications of current strategies and be useful for the development of novel technologies to prevent or eliminate A. flavus and aflatoxins in food and feed during storage.

Development of isotope dilution-ultrahigh-performance liquid chromatography-tandem mass spectrometry for the accurate determination of aflatoxins in grains

A method for the accurate determination of aflatoxin B1, B2, G1, and G2 in grains was established using isotope dilution-ultrahigh-performance liquid chromatography-tandem mass spectrometry (ID-UHPLCMS/MS). 13C- labeled aflatoxins (AFs) were used as internal standards. AFs were extracted with a mixture of methanol/water (60/40; v/v) and purified using an immunoaffinity column (IAC) for adequate elimination of matrix interferences. The method showed excellent analytical performance over the studied range (0.5–4 µg/kg). The limits of detection (0.002–0.005 µg/kg) and quantification (0.007–0.011 µg/kg) were substantially lower than the maximum level fixed by the European Union for grain cereals. The accuracy values ranged from 97 % to 103 % for all AFs, with intraday and interday precisions ranging from 1.8 % to 3.0 % and 0.3–3.8 % relative standard deviation (RSD), respectively. The measurement uncertainty was less than 4.20 %. The developed method shows high-order metrological quality with superior performance over the existing analytical methods. The practical applicability of the method was demonstrated by the measurement of AFs in different grain samples.

Inhibitory effect of volatile organic compounds from Bacillus flexus TR-1 against Aspergillus flavus and aflatoxins in grains during storage

Inhibitory effect of volatile organic compounds from Bacillus flexus TR-1 against Aspergillus flavus and aflatoxins in grains during storage

The Inhibitory Effect of Pseudomonas stutzeri YM6 on Aspergillus flavus Growth and Aflatoxins Production by the Production of Volatile Dimethyl Trisulfide.

Aspergillus flavus and the produced aflatoxins cause great hazards to food security and human health across all countries. The control of A. flavus and aflatoxins in grains during storage is of great significance to humans. In the current study, bacteria strain YM6 isolated from sea sediment was demonstrated effective in controlling A. flavus by the production of anti-fungal volatiles. According to morphological characteristics and phylogenetic analysis, strain YM6 was identified as Pseudomonas stutzeri. YM6 can produce abundant volatile compounds which could inhibit mycelial growth and conidial germination of A. flavus. Moreover, it greatly prevented fungal infection and aflatoxin production on maize and peanuts during storage. The inhibition rate was 100%. Scanning electron microscopy further supported that the volatiles could destroy the cell structure of A. flavus and prevent conidia germination on the grain surface. Gas chromatography/mass spectrometry revealed that dimethyl trisulfide (DMTS) with a relative abundance of 13% is the most abundant fraction in the volatiles from strain YM6. The minimal inhibitory concentration of DMTS to A. flavus conidia is 200 µL/L (compound volume/airspace volume). Thus, we concluded that Pseudomonas stutzeri YM6 and the produced DMTS showed great inhibition to A. flavus, which could be considered as effective biocontrol agents in further application.

Design of hyper-cross-linked polymers with tunable polarity for effective preconcentration of aflatoxins in grain

Aflatoxins (AFs) as a category of polar mycotoxins possess a significant threat to human health. However, constructing of sorbents with suitable polarity for the preconcentration of AFs remains poorly developed due to the difficulty in tuning the polarity of the sorbents optionally. Herein, a series of novel hypercrosslinked polymers (OP-HCPs) with adjustable polarity were designed and synthesized by varying selection of alkylphenol ethoxylates monomers and benzyl halides crosslinkers for the preconcentration of AFs. By integration of magnetism into OP-HCP, a novel magnetic sorbent (M-OP10-DCX) was prepared to readily pre-concentrate of AFs from rice and maize samples prior to high performance liquid chromatography-fluorescence detection (HPLC-FD). Benefiting from the unique polarity interaction between M-OP10-DCX and AFs, the M-OP10-DCX displayed excellent adsorption ability for the AFs. Good linearity in the range of 5.0–4000 pg g−1 (R2 > 0.9983), low limits of detection (signal-to-noise ratio of 3) of 1.5–50 pg g−1 and high enrichment factors of 105–205 were achieved. The recoveries of the method ranged from 82.8 % to 115 % with the relative standard deviation less than 8.0 %. This work provided a new strategy for the rational design of HCPs with tunable polarity as valuable tools for specific adsorption of different kinds of compounds.

The One Nutrition in Complex Environments (ONCE) study protocol: a cluster-randomized multi-level multi-sectoral intervention to improve nutrition in Uganda

ObjectiveTo implement and measure the effects of a multi-level multi-sectoral social behavior change (SBC) intervention in Agago District of Northern Uganda and to determine the potential for scale-up.InterventionCompare the Nutrition Impact and Positive Practice (NIPP) approach to a NIPP+ approach. The NIPP approach involves nutrition education and SBC, whereas the NIPP+ adds agricultural inputs, training, and tools to support improved farm and water quality practices. The intervention effect will be measured through lower levels of aflatoxin in grain, lower water contamination, and improved knowledge on nutrition and health.DesignThis is a three-arm cluster-randomized controlled superiority trial (cRCT). The study arms include the following: group 1: NIPP; group 2: NIPP+, and group 3: control. Groups 1 and 2 will receive a 12-week intervention (NIPP or NIPP+) with active monitoring and longitudinal follow-up at 2, 6, and 12 months post-intervention. Additionally, an in-depth process and performance evaluation of each intervention arm will be undertaken using quantitative and qualitative methods. A total of 60 clusters from 5 subcounties of the Agago district will be randomly selected, and 15 households per cluster will be recruited using specific inclusion/exclusion criteria for a total of 900 households (300/arm). Respondents for the qualitative portion will be purposely selected.AnalysisWe will collect data from all participants at 3 time points: baseline, endline, and 12 months post-intervention. The analysis will utilize intent-to-treat (ITT) using the initial randomization of the treatment arms to determine the overall impact of having the NIPP vs. NIPP+ vs. control. Mixed effects models will be used to determine the role of time-variant and invariant individual household, and community characteristics, as well as measures of exposure and integration on key outcome indicators. A difference-in-difference analysis (baseline/endline, baseline/12 months post-intervention, endline/12 months post-intervention) will also be used to triangulate findings.Trial registrationNCT04209569. One Nutrition in Complex Environments (ONCE) Registered 24 December 2019

Ozone to Overcome Aspergillus flavus and Aflatoxin in Grains: Opportunities and Challenges of Implementation

<p>Ozone can be used as an alternative to control mold and aflatoxins in grains that is more eco-friendly because it does not leave residues that are harmful for humans, animals and environment. The use of ozone was quite effective in reducing mold and aflatoxin in grains such as barley, whole wheat, corn and rice. In Indonesia, ozone was limited used for sterilization of fruit and vegetable. Therefore, the comprehensive review on the potential of ozone in grains is needed, especially on the priority commodities of agricultural development in Indonesia, such as rice and corn. The objective of this review was to examine the opportunities of ozone to reduce Aspergillus flavus and aflatoxin in grains, so that it can improve its quality and shelf life. Many studies showed that the use of ozone reduced Aspergillus flavus and aflatoxin in grains by 50-90%.<br />Keywords: Grains, Aspergillus flavus, aflatoxin, ozone</p><p> </p><p><strong>Abstrak</strong></p><p><strong>OZON UNTUK MENGATASI CEMARAN ASPERGILLUS FLAVUS DAN</strong><br /><strong>AFLATOKSIN PADA BIJI-BIJIAN: PELUANG DAN TANTANGAN</strong><br /><strong>IMPLEMENTASI</strong></p><p>Ozon dapat digunakan sebagai salah satu alternatif pengendalian cendawan dan aflatoksin pada biji-bijian yang lebih ramah lingkungan karena tidak meninggalkan residu yang berbahaya bagi manusia, hewan, maupun lingkungan. Penggunaan ozon cukup efektif mengurangi kontaminasi cendawan dan aflatoksin pada bijibijian seperti barley, biji gandum, jagung, dan beras. Di Indonesia, ozon digunakan secara terbatas untuk proses pencucian beberapa jenis buah dan sayuran. Oleh karena itu diperlukan telaah lebih lanjut mengenai potensi penggunaan ozon pada biji-bijian terutama komoditas strategis yang menjadi prioritas dalam pembangunan pertanian di Indonesia seperti padi dan jagung. Tujuan dari tulisan ini adalah untuk menelaah peluang penggunaan ozon dalam mengurangi kontaminasi Aspergillus flavus dan cemaran aflatoksin pada produk biji-bijian, sehingga diharapkan dapat memperbaiki kualitas dan meningkatkan umur simpan produk. Hasil penelitian menunjukkan penggunaan ozon dapat menurunkan cemaran A. flavus dan aflatoksin pada biji-bijian sampai 50-90%.<br />Kata kunci: Biji-bijian, Aspergillus flavus, aflatoksin, ozon</p>

Preparation and properties of aflatoxins imprinted polymer grafted onto the surface of mesoporous silica SBA-15 functionalized with double bonds.

Mesoporous silica Santa Barbara-15 was functionalized by methacryloxypropyl trimethoxysilane. Taking this as the carrier material, a new mesoporous silica surface imprinted polymer was synthesized by using the C=C bond, functional monomer α-methacrylic acid, and crosslinker ethylene glycol dimethacrylate, which was used to extract aflatoxin from grain efficiently. It is different from the preparation of surface imprinted polymers which is physically wrapping carrier materials with polymer layers. The chemical grafting method makes the coating of the polymer layer more controllable. A new method for selective separation, enrichment, and determination of trace aflatoxin in grain was established by using the polymers as the filter of the solid-phase extraction column and high-performance liquid chromatography. The linear range of the method was 0.5-100 μg/kg, R2 =0.9990-0.9993. The recovery of aflatoxin G2, G1, B2, and B1 was 98.9-119.7% and the relative standard deviation was 3.07-5.76%. By comparing the self-made column with the immunoaffinity column, it was found that the self-made column had better extraction performance for aflatoxins than the immunoaffinity column. It can be used for the analysis and detection of aflatoxins in cereal.

English

In Burkina Faso, groundnut (Arachis hypogaea L.) is produced in almost the entire country except the north. Its multiple uses make it a highly appreciated oil seeds and leguminous crop. However, the presence of aflatoxins in grains constitutes a public health risk and thus limits its marketing to international markets. The present study evaluated sixteen (16) short duration (90 days) groundnut varieties (15 varieties received from ICRISAT Mali and one variety from INERA). The main goal was to evaluate the agronomic performance and the level of resistance of each variety to total aflatoxins in two locations (Gampela and Tenkodogo). The design was Blocks of Fisher completely randomized with three (3) replications and two factors were studied: The variety at sixteen (16) levels and the location at two (2) levels. The average pods yields were above 1 ton in the 2 locations. The best yields were observed from ICGV-IS 13806 (2394.97 kg.ha-1) at Gampela and ICGV-IS 13912 (1804.78 kg.ha-1) at Tenkodogo. In both locations, Aspergillus flavus/parasiticus contamination rates and the aflatoxin contamination amounts of the varieties were low (0 - 3.9 ppb). Aflatoxin contents varied depending on the degree of maturity of the seeds: Thus immature seeds (M3) had higher aflatoxin contents than mature seeds (M2 and M1). These low levels are the result of strict application of good agronomic practices and sorting. The negative correlation between the percentage of maturity of grains and the aflatoxins contents and the positive correlation between the percentage of maturity of grains and the shelling ratio indicate that an early sowing allowed good filling of pods and then the very significant reduction of aflatoxins contamination. The positive correlation also between the shelling ratio and the pods yields shows that when the pods are full they weigh more and increase the yield. However, the varieties to be adopted by producers must have good technological characteristics such as good shelling ratio and good weights of 100 seeds and less pods and seeds damaged. Varieties that would meet these criteria would be ICGV-IS 13824, ICGV-IS 13834 and ICGV-IS 13912. Key words: Aflatoxins contaminations, groundnut, locations, varieties, yields.

Separation and quantification of aflatoxins in grains using modified dispersive liquid–liquid microextraction combined with high-performance liquid chromatography

A simple modified dispersive liquid–liquid microextraction was applied for the rapid separation of aflatoxin B1 (AFB1) and aflatoxin B2 (AFB2) from grain. The extracted aflatoxins (AFs) were quantified by high-performance liquid chromatography equipped fluorescence detector. The several analytical factors affecting the microextraction efficiency such as sample volume, sample pH, type and volume of extractant, salt concentration, and the number of injections were studied. At the optimum properties, the calibration curves of AFB1 and AFB2 were linear in the concentration range of 50.0–500.0 ng/kg and 35.0–400.0 ng/kg, respectively. The limits of detection were found to be 15.0 ng/kg for AFB1 and 10.0 ng/kg for AFB2. The inter-day and intra-day relative standard deviations (RSD%) for AFB1 and AFB2 were in the range of 4.7–8.1%. The developed technique was successfully used in the separation and quantification of AFB1 and AFB2 in real samples.

An amino-functionalized zirconium-based metal-organic framework of type UiO-66-NH2 covered with a molecularly imprinted polymer as a sorbent for the extraction of aflatoxins AFB1, AFB2, AFG1 and AFG2 from grain.

A surface imprinted polymer of type UiO-66-NH2@MIP was prepared by combining molecular imprinted polymers (MIPs) and an amino-functionalized zirconium-based metal-organic framework. Quercetin is used as the virtual template, UiO-66-NH2 acts as the carrier to which the monomer acrylamide can be copolymerized. The material was characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. It was used as a sorbent in a solid-phase extraction column. The extraction conditions were optimized. The adsorption capacities for aflatoxins AFB1, AFB2, AFG1 and AFG2 by this SPE and by the commercial SPE were compared. The method was successfully applied to quantify the aflatoxins in grain. Figures of merit include (a) good linearity (range from 0.20-45μg·kg-1) with R2 (range from 0.9986-0.9994), (b) low detection limits (90-130ng·kg-1), (c) acceptable reproducibility (1.0-5.9%; for n= 6), and (d) relatively satisfactory recovery rates (74.3-98.6%). The new sorbent has good selectivity and reusability. Graphical abstractUiO-66-NH2@MIPs were synthesized with modified UIO-66-NH2 as core and quercetin as pseudo template. A cartridge was prepared with the polymers as the sorbent, and its performance was compared with different commercial SPE cartridges.

A Novel Niosome-Encapsulated Essential Oil Formulation to Prevent Aspergillus flavus Growth and Aflatoxin Contamination of Maize Grains During Storage.

Aflatoxin (AF) contamination of maize is a major concern for food safety. The use of chemical fungicides is controversial, and it is necessary to develop new effective methods to control Aspergillus flavus growth and, therefore, to avoid the presence of AFs in grains. In this work, we tested in vitro the effect of six essential oils (EOs) extracted from aromatic plants. We selected those from Satureja montana and Origanum virens because they show high levels of antifungal and antitoxigenic activity at low concentrations against A. flavus. EOs are highly volatile compounds and we have developed a new niosome-based encapsulation method to extend their shelf life and activity. These new formulations have been successfully applied to reduce fungal growth and AF accumulation in maize grains in a small-scale test, as well as placing the maize into polypropylene woven bags to simulate common storage conditions. In this latter case, the antifungal properties lasted up to 75 days after the first application.

An Automated and High-Throughput Immunoaffinity Magnetic Bead-Based Sample Clean-Up Platform for the Determination of Aflatoxins in Grains and Oils Using UPLC-FLD.

Sample clean-up remains the most time-consuming and error-prone step in the whole analytical procedure for aflatoxins (AFTs) analysis. Herein, an automated and high-throughput sample clean-up platform was developed with a disposable, cost-effective immunoaffinity magnetic bead-based kit. Under optimized conditions, the automated method takes less than 30 min to simultaneously purify 20 samples without requiring any centrifugation or filtering steps. When coupled to ultra-high performance liquid chromatography with fluorescence detection, this new analysis method displays excellent accuracy and precision as well as outstanding efficiency. Furthermore, an interlaboratory study was performed in six laboratories to validate the novel protocol. Mean recovery, repeatability, reproducibility, and Horwitz ratio values were within 91.9%–107.4%, 2.5%–7.4%, 2.7%–10.6%, and 0.26%–0.90, respectively. Results demonstrate that the developed sample clean-up platform is a reliable alternative to most widely adopted clean-up procedures for AFTs in cereals and oils.

Association between agronomic traits and aflatoxin accumulation in diverse maize lines grown under two soil nitrogen levels in Eastern Kenya

Aflatoxin accumulation in maize is strongly influenced by the environment in which the crop is grown. To gain insights into the ways in which soil fertility influences aflatoxin, we investigated the relationships between agronomic traits and aflatoxin in diverse maize testcrosses that were grown under two nitrogen treatment levels. The experiment was conducted in Eastern Kenya, an aflatoxin-endemic area, with natural Aspergillus flavus inoculum. A panel of 205 maize lines was grown under low soil nitrogen (Nlow=26kg/ha applied N) in the long season of 2011 and a subset of the genotypes (n=123) was grown under high soil nitrogen (Nhigh=114kg/ha applied N) in the short season of 2010 and long season of 2011. Kernel traits, grain yield, days to anthesis, ear rot, and aflatoxin were analyzed for the panel. Grain yield, protein, and kernel bulk density were higher in maize grown under Nhigh compared to maize grown under Nlow, with grain yield twice as high under Nhigh. A higher proportion of plots had grain with detectable aflatoxin under Nlow than under the Nhigh. When the maize testcrosses were grouped into three maturity categories based on days to anthesis, aflatoxin accumulation was twice as high in the late-maturing group than in the other two categories under Nlow. The proportion of aflatoxin contamination was higher in dent than in flint maize. However, the extent of aflatoxin accumulation did not differ significantly (P>0.05) over the entire testcross panel, among maize genotypes within the maturity groups or among kernel texture groups within the maturity groups. Kernel bulk density and protein content were higher in early and intermediate groups than in the late maturity group. Grain yield did not differ among the maturity groups (P>0.05), but significant positive correlations were observed between the proportion of grain yield reduction due to low soil nitrogen stress and aflatoxin in early and late maturity groups. Kernel bulk density was negatively correlated with aflatoxin in grain. No significant association was observed between aflatoxin and ear rot or kernel size. We conclude that aflatoxin mitigation strategies should include soil nitrogen amendment and breeding approaches that include selection for the correlated agronomic traits.

A Concise History of Mycotoxin Research.

Toxigenic fungi and mycotoxins entered human food supplies about the time when mankind first began to cultivate crops and to store them from one season to the next, perhaps 10,000 years ago. The storage of cereals probably initiated the transition by mankind from hunter-gatherer to cultivator, at the same time providing a vast new ecological niche for fungi pathogenic on grain crops or saprophytic on harvested grain, many of which produced mycotoxins. Grains have always been the major source of mycotoxins in the diet of man and his domestic animals. In the historical context, ergotism from Claviceps purpurea in rye has been known probably for more than 2000 years and caused the deaths of many thousands of people in Europe in the last millennium. Known in Japan since the 17th century, acute cardiac beriberi associated with the consumption of moldy rice was found to be due to citreoviridin produced by Penicillium citreonigrum. This toxin was believed to be only of historic importance until its reemergence in Brazil a few years ago. Other Penicillium toxins, including ochratoxin A, once considered to be a possible cause of Balkan endemic nephropathy, are treated in a historical context. The role of Fusarium toxins in human and animal health, especially T-2 toxin in alimentary toxic aleukia in Russia in the 1940s and fumonisins in equine leucoencephalomalasia, is set out in some detail. Finally, this paper documents the story of the research that led to our current understanding of the formation of aflatoxins in grains and nuts, due to the growth of Aspergillus flavus and its role, in synergy with the hepatitis B virus, in human liver cancer. During a period of climate change and greatly reduced crop diversity on a global basis, researchers tasked with monitoring the food system need to be aware of fungal toxins that might have been rare in their working careers that can reappear.

Aflatoxin Accumulation in a Maize Diallel Cross

Aflatoxins, produced by the fungus Aspergillus flavus, occur naturally in maize. Contamination of maize grain with aflatoxin is a major food and feed safety problem and greatly reduces the value of the grain. Plant resistance is generally considered a highly desirable approach to reduction or elimination of aflatoxin in maize grain. In this investigation, a diallel cross was produced by crossing 10 inbred lines with varying degrees of resistance to aflatoxin accumulation in all possible combinations. Three lines that previously developed and released as sources of resistance to aflatoxin accumulation were included as parents. The 10 parental inbred lines and the 45 single crosses making up the diallel cross were evaluated for aflatoxin accumulation in field tests conducted in 2013 and 2014. Plants were inoculated with an A. flavus spore suspension seven days after silk emergence. Ears were harvested approximately 60 days later and concentration of aflatoxin in the grain determined. Parental inbred lines Mp717, Mp313E, and Mp719 exhibited low levels (3–12 ng/g) of aflatoxin accumulation. In the diallel analysis, both general and specific combining ability were significant sources of variation in the inheritance of resistance to aflatoxin accumulation. General combining ability effects for reduced aflatoxin accumulation were greatest for Mp494, Mp719, and Mp717. These lines should be especially useful in breeding for resistance to aflatoxin accumulation. Breeding strategies, such as reciprocal recurrent selection, would be appropriate.

Aflatoxin Sampling and Testing Proficiency in the Texas Grain Industry

Aflatoxin is a group I carcinogen and represents a significant public health and food safety risk throughout the world. Aflatoxin contaminated cereals and oilseeds that contain greater than 20 μg/kg of the toxin (B1, B2, G1, G2) are defined as adulterated by the Texas Commercial Feed Rules and are regulated by the Texas Feed and Fertilizer Control Service. This study was performed to assess sampling and testing of maize for aflatoxin contamination. During 2010, 87 Texas grain elevators’ sampling procedures were assessed and a second investigation documented aflatoxin analysis procedures at 41 grain elevator establishments. The average sample size was 1.8 kg (4 pounds) and fewer than 20% of the grain elevators collected samples using an official (prescribed) sampling pattern by the grain inspection, crop insurance or regulatory authorities within the United States. Proficiency samples were analyzed by 39 cooperating grain elevators and 7 firms accurately analyzed samples containing greater than 300 μg/kg aflatoxin. While sampling contributes to variability in measuring aflatoxin in grain, this study highlights that aflatoxin analysis using commercially available test kits is a major contributor to variation in aflatoxin test results among commercial grain handlers.

Anti-idiotypic nanobody-phage based real-time immuno-PCR for detection of hepatocarcinogen aflatoxin in grains and feedstuffs.

Aflatoxins are a group of extremely toxic small molecules that have been involved in human hepatic and extrahepatic carcinogenesis as causative agents. Herein, we developed a real-time immuno polymerase chain reaction (IPCR) assay for the accurately quantitative detection of aflatoxins in agri-products base on a M13 phage containing aflatoxin anti-idiotypic nanobody and its encoding DNA which was used to design the specific primers. The limit of detection (LOD) of the assay is 0.02 ng/mL, which exhibits a 4-fold improvement over traditional phage ELISA. The developed method was successfully validated with the samples of corn, rice, peanut, and feedstuff, which are major aflatoxin-contaminated agri-products. And the recoveries were from 77.05 to 122.16%. For further validation, the developed assay was also compared with a reference HPLC method for the analysis of aflatoxins in corn and peanuts, and concordant results (R(2) = 0.991) were obtained. In this context, this study provides a novel opportunity to analyze aflatoxins in agri-products.

Fluorescence Excitation–Emission Features of Aflatoxin and Related Secondary Metabolites and Their Application for Rapid Detection of Mycotoxins

The persistent occurrence of aflatoxins in food and feed remains a problem for producers of commodities subject to colonization with toxigenic molds. Aflatoxins are secondary metabolites of fungi of the Aspergillus spp. associated with deleterious health effects. Because current screening methods for these toxins are lengthy, destructive, and costly, there is a continuous search for a more rapid, noninvasive, and cost-effective technology. The present study utilized a fluorescence excitation–emission matrix (EEM) of aflatoxin as well as two additional secondary metabolites (kojic acid and the bright greenish-yellow fluorescence (BGYF) compound) of Aspergillus flavus measured with a fluorescence spectrophotometer. The results were compared to image data acquired with a fluorescence hyperspectral sensor in order to evaluate the potential of image-based technology for detecting aflatoxin in grain. The excitation–emission matrix of aflatoxin B1 standard produced overlapping peaks in 340–400 nm of excitation range emitting in the blue range at around 450 nm. The spectral signature extracted from the hyperspectral image was also in the blue range, emitting blue fluorescence. Because the results from both systems were comparable, where all fluorescence peaks were in the blue range, the present study validates the feasibility of image-based technology for nondestructive detection of aflatoxin in corn. Additional peaks were revealed in the aflatoxin EEM in the 260-nm excitation range that were not present in the kojic acid and BGYF compound mixture. This new information allows for the separation of the aflatoxin signature from the potentially confounding overlap of other secondary metabolites occurring in the blue and blue-green spectral ranges.

Fluorescence Imaging Spectroscopy (FIS) for Comparing Spectra from Corn Ears Naturally and Artificially Infected with Aflatoxin Producing Fungus

In an effort to address the problem of rapid detection of aflatoxin in grain, particularly oilseeds, the current study assessed the spectral differences of aflatoxin production in kernels from a cornfield inoculated with spores from 2 different strains of toxigenic Aspergillus flavus. Aflatoxin production in corn from the same field due to natural infestation was also assessed. A small corn plot in Baton Rouge, La., U.S.A., was used during the 2008-growing season. Two groups of 400 plants were inoculated with 2 different inocula and 1 group of 400 plants was designated as controls. Any contamination detected in the controls was attributed to natural infestation. A subset of each group was imaged with a visible near infra red (VNIR) hyperspectral system under ultra violet (UV) excitation and subsequently analyzed for aflatoxin using affinity column fluorometry. Group differences were statistically analyzed. Results indicate that when all the spectral data across all groups were averaged, any potential differences between groups (treated and untreated) were obscured. However, spectral analysis based on contaminated "hot" pixel classification showed a distinct spectral shift/separation between contaminated and clean ears with fluorescence peaks at 501 and 478 nm, respectively. All inoculated and naturally infected control ears had fluorescence peaks at 501 nm that differed from uninfected corn ears. Results from this study may be useful in evaluating rapid, noninvasive instrumentation and/or methodology for aflatoxin detection in grain.