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United States Department of Agriculture

Agricultural Research Service

Title: Method for detecting fecal contamination on the surface of fruits or vegetables using visible light fluorescent spectroscopy
See also: US Patent Office Full Record

Patent Number: 7547508
Docket Number: 1804
Serial Number: 11304381
Date Patented: 06/16/2009


Summary: Time-dependent differences in fluorescence responses of normal surfaces of the fruit or vegetable as opposed to surfaces which are contaminated with feces, may be used for improved detection of feces-contaminated fruits and vegetables. In this process, the surface of a fruit or vegetable which contains a native chlorophyll is illuminated with a pulse of UV or visible light having a wavelength effective to elicit fluorescence of feces of a plant consuming animal. The intensity of fluorescent light emissions from the surface are measured at one or more wavelengths characteristic of the emission spectra of chlorophyll or its degradation products, at a nanosecond-scale time period or window which is after the peak emission of the native chlorophyll of the fruit or vegetable. The presence of fecal contamination is determined by comparing this measured intensity to a threshold value of the intensity of fluorescent light emissions for a non-feces contaminated control of the same fruit or vegetable measured at substantially the same conditions, substantially the same said time period, and at substantially the same said wavelengths. A determination that the measured intensity of the fluorescent light emissions is significantly greater than the threshold value is an indication of the presence of fecal material on the surface of the fruit or vegetable.

Patent Status: Patent issued on June 16, 2009. Link at USPTO filed under patent title “Use of nanosecond scale, time-resolved, imaging to differentiate contemporaneous fluorescence responses from multiple substances.”


Moon S. Kim
Environmental Microbial and Food Safety Laboratory
BELTSVILLE, MD, 20705-2350
Phone: (301) 504-8450
Fax: (301) 504-9466  

Alan Marc. Lefcourt
(same address as first inventor)
Phone: (301) 504-8450
Fax: (301) 504-9466

Yud-Ren Chen
(former ARS employee)


Last Modified: 10/1/2015
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