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United States Department of Agriculture

Agricultural Research Service

Title: Detection of Fecal and Ingesta Contamination on Meat Surfaces Utilizing Intrinsic Fluorescent Markers

item Casey, Thomas
item Rasmussen, Mark

Submitted to: American Society for Microbiology Branch Meeting
Publication Type: Abstract Only
Publication Acceptance Date: October 16, 1999
Publication Date: N/A

Technical Abstract: Public concern over E. coli O157:H7 has risen dramatically over the past several years. Ingestion of undercooked meat containing these bacteria leads to serious illness and possible death. E. coli O157:H7 is found in the feces of livestock and is spread to the meat carcass by fecal contamination during processing. We describe a method based upon fluorescence spectroscopy to detect the feces, the substrate for the bacteria. This method allows for a quick instantaneous, determination of meat contamination. The resulting signal is obtained with a time constant on the order of 100 ms, which will allow for the detection to occur on the production line of the meat production facility. Fluorescent markers, such as Chlorophyll a metabolites in the feces, are detected by fluorescence in the red part of the visible spectrum when excited by green laser light that is modulated, to incorporate phase-sensitive detection, and coupled through a fiber optic. The fluorescence is coupled through the same fiber or a different fiber onto photomultiplier tube detectors. All components of the system have been built into a detector that can be easily handled and carried. Pheophorbide a, one of the major Chlorophyll a metabolites, can be detected to a limit on the order of 10**-9 M in solution.

Last Modified: 4/22/2015