Progress 10/01/12 to 09/30/13
Outputs
Progress Report Objectives (from AD-416): Identify and quantify aflatoxin-producing fungi on corn, using a non- destructive hyperspectral imaging system. Produce spectral libraries for fungus alone and in infected corn. Determine spectral differences between different corn varieties, resistant and susceptible to aflatoxin contamination and infected and un-infected with aflatoxin producing fungi. Develop rapid, non-destructive hyperspectral imaging methodology to measure fungal growth and aflatoxin in corn kernels and spectral signatures associated with traits for resistance to fungal infection and aflatoxin contamination in corn kernels. Test system's effectiveness in laboratory and field situations. Approach (from AD-416): Corn kernel varieties with varying levels of resistance to aflatoxin producing fungi will be collected and imaged using a tabletop hyperspectral scanning imaging system. Kernels will be spectrally analyzed to determine how much the UV, visible, and near infrared portions of the electromagnetic spectrum differ from one corn variety to another. Cultures of aflatoxin producing and non-producing fungi will also be imaged and the spectral fingerprints will be collected to produce a "spectral library" of the different strains of fungi. These data will be used to determine if hyperspectral imaging can then be used to differentiate and quantitate the varying fungal strains and/or their aflatoxin production both in pure fungal culture and in fungally infected kernels from corn varieties either resistant or susceptible to aflatoxin contamination. Techniques also will be investigated during ongoing experiments to determine the best imaging environment in which to accomplish hyperspectral analyses, such as type and direction of lighting. Once appropriate algorithms are developed, the system will be tested in various laboratory and field experiments to determine the efficacy of the system. Lab experiments were conducted using green fluorescent protein (GFP) labeled toxigenic and atoxigenic Aspergillus (A.) flavus in order to visualize competition between the two strains. Results show a suppression of the toxin producing strain by the atoxigenic strain of the fungus. Overall, the aflatoxin signature was studied from both chemical (pure, extracted) and biological (associated with A. flavus contaminated field and lab corn) perspectives. Data from the studies were summarized in several publications and a patent "Method and Detection System for Detection of Aflatoxin in Corn with Fluorescence Spectra" was approved. Additional experiments were designed to address the detection potential of hyperspectral�based instrumentation (collecting and processing information across electromagnetic spectrum) of aflatoxin contamination on whole maize ears. A rotational stage was designed and subsequently developed to accommodate whole ears during a 360 degree rotation, producing a flat image representation of each ear. The stage was tested for image acquisition of whole maize ear data under both halogen and ultra violet (UV) illumination. In addition to maze ears, the system may be utilized for imaging other cylindrical or circular objects for food safety or related applications. This technology was developed under a grant from Bill & Melinda Gates Foundation Grand Challenge Exploration (GCE round 8), awarded in 2012. The goal of the grant is to develop portable technology to detect aflatoxin contamination in single corn ears for farmers in the developing countries. The Gates project is a joint effort between Mississippi State University and ARS-SRRC to extend knowledge gained from the collaborative project to more practical applications. Significant emphasis over this past year was placed on reviewing and summarizing data of numerous lab and field experiments previously conducted, to capture significant discoveries/concepts useful towards the aflatoxin detection/quantitation mission. This review and summary procedure was also necessary for the development of manuscripts for publication in refereed journals.
Impacts
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Publications
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Progress 10/01/11 to 09/30/12
Outputs
Progress Report Objectives (from AD-416): Identify and quantify aflatoxin-producing fungi on corn, using a non- destructive hyperspectral imaging system. Produce spectral libraries for fungus alone and in infected corn. Determine spectral differences between different corn varieties, resistant and susceptible to aflatoxin contamination and infected and un-infected with aflatoxin producing fungi. Develop rapid, non-destructive hyperspectral imaging methodology to measure fungal growth and aflatoxin in corn kernels and spectral signatures associated with traits for resistance to fungal infection and aflatoxin contamination in corn kernels. Test system's effectiveness in laboratory and field situations. Approach (from AD-416): Corn kernel varieties with varying levels of resistance to aflatoxin producing fungi will be collected and imaged using a tabletop hyperspectral scanning imaging system. Kernels will be spectrally analyzed to determine how much the UV, visible, and near infrared portions of the electromagnetic spectrum differ from one corn variety to another. Cultures of aflatoxin producing and non-producing fungi will also be imaged and the spectral fingerprints will be collected to produce a "spectral library" of the different strains of fungi. These data will be used to determine if hyperspectral imaging can then be used to differentiate and quantitate the varying fungal strains and/or their aflatoxin production both in pure fungal culture and in fungally infected kernels from corn varieties either resistant or susceptible to aflatoxin contamination. Techniques also will be investigated during ongoing experiments to determine the best imaging environment in which to accomplish hyperspectral analyses, such as type and direction of lighting. Once appropriate algorithms are developed, the system will be tested in various laboratory and field experiments to determine the efficacy of the system. Studies were directed into differentiating the responses from corn kernels infected with aflatoxin-producing and non-aflatoxin-producing Aspergillus (A.) flavus. The internal parts of the infected corn kernels were also imaged with the hyperspectral (beyond visible spectrum of light) imager and a Scanning Electron Microscope. These studies were expected to provide deeper understanding of the biological processes involved during Aspergillus flavus infection of corn kernels. The purity of the aflatoxin signal was investigated by comparing the hyperspectral signature of pure and extracted aflatoxin with signatures produced by excitation-emission matrix fluorescence. The extracted aflatoxin was further tested in a mass-spectrometer /high-performance liquid chromatography (instruments used to determine chemical make-up). Additional experiments were conducted using green fluorescent protein (GFP) labeled toxigenic and atoxigenic A. flavus in order to visualize competition between the two strains. Overall, the aflatoxin signature was studied from both chemical (pure, extracted) and biological (associated with A. flavus contaminated field and lab corn) perspective. The 1 kg sample processing demonstration system is in the final testing and refinement phase. Data was collected for statistical purposes and analysis is under way.
Impacts
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Publications
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Progress 10/01/10 to 09/30/11
Outputs
Progress Report Objectives (from AD-416) Identify and quantify aflatoxin-producing fungi on corn, using a non- destructive hyperspectral imaging system. Produce spectral libraries for fungus alone and in infected corn. Determine spectral differences between different corn varieties, resistant and susceptible to aflatoxin contamination and infected and un-infected with aflatoxin producing fungi. Develop rapid, non-destructive hyperspectral imaging methodology to measure fungal growth and aflatoxin in corn kernels and spectral signatures associated with traits for resistance to fungal infection and aflatoxin contamination in corn kernels. Test system's effectiveness in laboratory and field situations. Approach (from AD-416) Corn kernel varieties with varying levels of resistance to aflatoxin producing fungi will be collected and imaged using a tabletop hyperspectral scanning imaging system. Kernels will be spectrally analyzed to determine how much the UV, visible, and near infrared portions of the electromagnetic spectrum differ from one corn variety to another. Cultures of aflatoxin producing and non-producing fungi will also be imaged and the spectral fingerprints will be collected to produce a "spectral library" of the different strains of fungi. These data will be used to determine if hyperspectral imaging can then be used to differentiate and quantitate the varying fungal strains and/or their aflatoxin production both in pure fungal culture and in fungally infected kernels from corn varieties either resistant or susceptible to aflatoxin contamination. Techniques also will be investigated during ongoing experiments to determine the best imaging environment in which to accomplish hyperspectral analyses, such as type and direction of lighting. Once appropriate algorithms are developed, the system will be tested in various laboratory and field experiments to determine the efficacy of the system. Based on the initial reflectance based imaging experiments, a fluorescence hyperspectral (using many individual wavelengths of light from visible light, as well as, ultraviolet to infrared) imaging system was developed and used to study fluorescence hyperspectral properties of healthy and aflatoxin- (a potent carcinogen) contaminated corn kernels. The contaminated corn kernels were prepared by inoculating corn ears with Aspergillus flavus spores in the field. After imaging, each corn kernel was examined for aflatoxin concentration using single kernel chemical analysis. The results indicate fluorescence hyperspectral imaging has the potential for detecting aflatoxin-contaminated corn. A Fluorescence Peak Shift (FPS) phenomenon was identified among groups of kernels with different aflatoxin contamination levels. The peak shifted toward longer wavelength, in the blue region, for the highly contaminated kernels and vice versa. Highly contaminated kernels also had a lower fluorescence peak magnitude compared with the less contaminated kernels. It was also found that a general negative correlation exists between measured aflatoxin and the fluorescence image bands in the blue and green spectral regions. Additionally, more studies were directed into differentiating the responses from corn kernels infected with aflatoxin-producing and non- aflatoxin-producing Aspergillus flavus. The internal parts of the infected corn kernels were also imaged with the hyperspectral imager and a Scanning Electron Microscope. These studies could provide deeper understanding of the biological processes involved during Aspergillus flavus infection of corn kernels. An aflatoxin detection algorithm (a defined set of mathematical parameters to achieve a result) is under development by using significant wavelengths identified in the analysis. The algorithm is used with the prototype fluorescence multi-spectral imaging system. The fluorescence multi-spectral imaging system will have the ability to tune to specific key wavelengths for aflatoxin detection and will be suitable for rapid detection and easy deployment. The system is currently being tested in scaled-up experiments where groups of corn kernels are examined simultaneously for the detection of aflatoxin. Each image includes 25 grams of corn, which is half the size of a standard sample for chemical analyses widely used in grain inspection stations. A 1 kg sample processing system is also in the final construction and testing phase. Success in these endeavors would bring us closer to our objective of providing a means of identifying/quantifying aflatoxin in corn using non-destructive hyperspectral imaging. Research progress was monitored through site visits, phone calls, and reports.
Impacts
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Publications
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Progress 10/01/09 to 09/30/10
Outputs
Progress Report Objectives (from AD-416) Identify and quantify aflatoxin-producing fungi on corn, using a non- destructive hyperspectral imaging system. Produce spectral libraries for fungus alone and in infected corn. Determine spectral differences between different corn varieties, resistant and susceptible to aflatoxin contamination and infected and un-infected with aflatoxin producing fungi. Develop rapid, non-destructive hyperspectral imaging methodology to measure fungal growth and aflatoxin in corn kernels and spectral signatures associated with traits for resistance to fungal infection and aflatoxin contamination in corn kernels. Test system's effectiveness in laboratory and field situations. Approach (from AD-416) Corn kernel varieties with varying levels of resistance to aflatoxin producing fungi will be collected and imaged using a tabletop hyperspectral scanning imaging system. Kernels will be spectrally analyzed to determine how much the UV, visible, and near infrared portions of the electromagnetic spectrum differ from one corn variety to another. Cultures of aflatoxin producing and non-producing fungi will also be imaged and the spectral fingerprints will be collected to produce a "spectral library" of the different strains of fungi. These data will be used to determine if hyperspectral imaging can then be used to differentiate and quantitate the varying fungal strains and/or their aflatoxin production both in pure fungal culture and in fungally infected kernels from corn varieties either resistant or susceptible to aflatoxin contamination. Techniques also will be investigated during ongoing experiments to determine the best imaging environment in which to accomplish hyperspectral analyses, such as type and direction of lighting. Once appropriate algorithms are developed, the system will be tested in various laboratory and field experiments to determine the efficacy of the system. Based on the initial reflectance based imaging experiments, a fluorescence hyperspectral (using many individual wavelengths of light from visible light, as well as, ultraviolet to infrared) imaging system was developed and used to study fluorescence hyperspectral properties of healthy and contaminated corn kernels. The contaminated corn kernels were prepared by inoculating corn ears with Aspergillus flavus spores in the field. After imaging, each corn kernel was examined for aflatoxin (a potent carcinogen) concentration using single kernel chemical analysis. The results indicate fluorescence hyperspectral imaging has the potential for detecting aflatoxin contaminated corn. A Fluorescence Peak Shift (FPS) phenomenon was identified among groups of kernels with different aflatoxin contamination levels. The peak shifted toward longer wavelength, in the blue region, for the highly contaminated kernels and vice versa. Highly contaminated kernels also had a lower fluorescence peak magnitude compared with the less contaminated kernels. It was also found that a general negative correlation exists between measured aflatoxin and the fluorescence image bands in the blue and green spectral regions. An aflatoxin detection algorithm (a defined set of mathematical parameters to achieve a result) is under development by using significant wavelengths identified in the analysis. The algorithm is used with the prototype fluorescence multi-spectral imaging system. The fluorescence multi-spectral imaging system will have the ability to tune to specific key wavelengths for aflatoxin detection and will be suitable for rapid detection and easy deployment. The system is currently being tested in scaled-up experiments where groups of corn kernels are examined simultaneously for the detection of aflatoxin. Each image includes 25 grams of corn, which is half the size of a standard sample for chemical analyses widely used in grain inspection stations. A 1 kg sample processing system is also in the construction phase, and will be tested in 2011. Research progress was monitored through teleconferencing, frequent email communications, and reports.
Impacts
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Publications
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