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United States Department of Agriculture

Agricultural Research Service


item Casey, Thomas
item Ashby, K
item Rasmussen, Mark
item Petrich, J

Submitted to: United States Japan Natural Resources Animal and Avian Health Panel
Publication Type: Abstract Only
Publication Acceptance Date: 9/26/2000
Publication Date: N/A
Citation: N/A

Interpretive Summary:

Technical Abstract: Public concern over E. coli O157:H7 and other foodborne pathogens has continued unabated during the past several years. Bacterial pathogens may be found in the feces of livestock and they are commonly spread to carcasses by fecal contamination during processing. While many methods detect or count actual bacteria, to determine if meat is contaminated, these methods require sample collection as well as extended incubation times. These methods are not amenable to real- time use by meat production plants. We describe a method based upon fluorescence spectroscopy to detect fecal contamination. This analytical device provides "instantaneous" determinations of carcass cleanliness. The detection device is based upon the fluorescence of chlorophyll metabolites present in fecal matter. These metabolites, when excited by a blue or green laser, fluoresce in the red region of the visible spectrum (670 nm). Clean meat carcasses present very low levels of background fluorescence in this region of the spectrum. In our prototype instrument, the excitation and emission light travel through a dual fiber optic that is coupled to a green (532 nm) laser excitation light source and to dichroic mirrors and photo multiplier tubes for discrimination and detection of the red emission light. The instrument can be operated under ambient light conditions. All components have been built into a small, portable instrument. Pheophorbide a, one of the major metabolites of dietary chlorophyll, can be detected to a limit of 10exp-9 M in solution. When developed as a complete imaging system, this technology will be an improvement over the current visual inspection process.

Last Modified: 10/17/2017
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