Submitted to: Proceedings of SPIE
Publication Type: Proceedings
Publication Acceptance Date: 9/15/2005
Publication Date: 12/15/2005
Citation: Hruska, Z., Yao, H., Dicrispino, K., Brabham, K., Lewis, D., Beach, J., Brown, R.L., Cleveland, T.E. 2005. Hyperspectral imaging of UVR effects on fungal spectrum. Proceedings of SPIE. 5886:58860V-1-9. 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 contamination from healthy grain. A collaboration between ARS-SRRC, Food and Feed Safety Research Unit and the Institute for Technology Development (ITD), Stennis Space Center, MS, is exploring the use of hyperspectral imaging non-destructive technology (developed by ITD) to detect/identify mycotoxin-producing fungi in grain products. In this investigation, the effects of ultraviolet radiation (UVR) on the hyperspectral imaging system’s ability to classify fungi were tested, since a UV lamp source may be used with the imaging system and a UV hyperspectral system itself may be used as well. It is important to obtain this information since UV effects on fungi are well-documented. Results demonstrate that even lethal doses of UVR have no immediate effect on hyperspectral imaging’s classification of fungi and that the UV light source may be safe to use when UV exposure time falls below 10 minutes. 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: The present report evaluated ultraviolet radiation (UVR) effects on the spectral signature of mycotoxin producing fungus, Aspergillus flavus. Ultraviolet radiation has long been used to reduce microbe contamination and to inactivate fungal spores. In view of the known effects of UVR on microorganisms, and because certain spectral bands in the signature of some fungi may be in the UV range, it is important to know the maximum acceptable limit of UVR exposure that does not significantly alter the fungal spectral signature and affect detection accuracy. A visible-near-infrared (VNIR) hyperspectral imaging system using focal plant push-broom scanning for high spatial and spectral resolution imaging was utilized to detect any changes. A. flavus cultures were grown for 5 days and imaged after intermittent or continuous UVR treatment. The intermittent group was treated at 1-minute intervals for 10 minutes, and VNIR images were taken after each UVR treatment. The continuous group was irradiated for 10 minutes and imaged before and after treatment. A control sample group did not undergo UVR treatment, but was also imaged at 1-minute intervals for 10 minutes in the same manner as the intermittent group. Before and after UVR treatment, mean fungal sample reflectance was obtained through spatial subset of the image, along with standard deviation, and pre- and post-treatment reflectance was compared for each sample. Results show significant difference between the reflectances of treated and control A. flavus cultures after 10 minutes of UV radiation. Additionally, the results demonstrate that even lethal light source used in the present experiment may be safe to use with the UV hyperspectral imaging system when exposure time falls below 10 minutes.