Location: Food and Feed Safety ResearchTitle: Fluorescence imaging spectroscopy (FIS) for comparing spectra from corn ears naturally and artificially infected with aflatoxin producing fungus ) Author
Submitted to: Journal of Food Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/15/2013
Publication Date: 8/30/2013
Citation: Hruska, Z., Yao, H., Kincaid, R., Darlington, D., Brown, R.L., Bhatnagar, D., Cleveland, T.E. 2013. Fluorescence imaging spectroscopy (FIS) for comparing spectra from corn ears naturally and artificially infected with aflatoxin producing fungus. Journal of Food Science. (78)8:1313-1320. Interpretive Summary: Aflatoxins are poisons produced by the fungus Aspergillus flavus after it infects agricultural commodities such as corn. Since aflatoxins in food and feed are regulated, enhanced ability to detect and measure fungal growth and aflatoxin contamination of corn could contribute significantly towards the separation of contaminated from healthy grain. A collaboration between ARS-SRRC, Food and Feed Safety Research Unit and Mississippi State University, Stennis Space Center, MS is exploring the use of hyperspectral imaging non-destructive technology (developed by ITD) to detect mycotoxin-producing fungi and mycotoxins in grain products. The present experiment compared spectral data from corn infected in the field with one or another of two toxigenic Aspergillus flavus fungal strains with noninoculated but sometimes naturally infected corn in the same field. Results showed a distinct spectral shift/separation between corn contaminated with aflatoxins (both naturally and artificially) and “clean” corn. Further experiments may lead to this technology being used to rapidly and accurately detect/measure Aspergillus flavus infection/aflatoxin contamination of corn without destruction of healthy grain. This could provide a useful tool to both growers and buyers in the corn industry that could enhance protection of food and feed as well as increase profits.
Technical Abstract: In an effort to address the aflatoxin problem in grain, the current study assessed the spectral differences of aflatoxin production in kernels from a cornfield inoculated with spores from two 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, Louisiana, was used during the 2008-growing season. Two groups of four hundred plants were inoculated with two different inoculums and one group of four hundred 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 chemically analyzed using affinity column fluorometry. Group differences were statistically analyzed. Results indicate that averaging all the spectral data across all groups obscured any potential differences between groups. 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 nm 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, non-invasive instrumentation and/or methodology for aflatoxin detection for the grain industry.