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Contamination Detection Method for Fruits and Vegetables

Opportunity: Method for detecting fecal contamination on the surface of fruits or vegetables using visible light fluorescent spectroscopy, available for licensing.

Laboratory: Beltsville Area Animal and Natural Resources Institute

Summary: Time-dependent differences in fluorescence responses of normal surfaces of the fruit or vegetable as opposed to surfaces that 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 that 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 is 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 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 Information:

  • Patent Number: 7547508
  • Docket Number: 1804
  • Serial Number: 11304381
  • Date Patented: 06/16/2009
  • Patent Status: Patent issued on June 16, 2009; filed under patent title “Use of nanosecond scale, time-resolved, imaging to differentiate contemporaneous fluorescence responses from multiple substances.”


Moon S. Kim, Alan Marc. Lefcourt, Environmental Microbial and Food Safety Laboratory; Yud-Ren Chen (former ARS employee)

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