Interactions of Insolation and Shading on Ability to Use Fluorescence Imaging to Detect Fecal Contaminated Spinach

Alan Lefcourt,Mark Siemens

doi:10.3390/app7101041

Abstract

Fecal contamination of produce in fields is a recognized food safety risk, and it is a requirement that fields be surveyed for evidence of fecal contamination. It may be possible to increase the efficacy of such surveys using imaging techniques that rely on detection of fluorescence responses of fecal material to UV excitation. However, fluorescence responses are easily masked by ambient illumination. This study investigated the potential of using a shroud to reduce the impact of ambient illumination on responses measured using relatively inexpensive optical components. During periods of near peak insolation, even with full shrouding, results indicate that reliable detection would be problematic. Towards dusk, effective imaging could be accomplished even with a gap of 250 cm at the bottom of the shroud. Results suggest that imaging using relatively inexpensive components could provide the basis for detection of fecal contamination in produce fields if surveys were conducted during dawn or dusk, or at night.

Highlights

Pathogens of fecal origin are the cause of most food-borne illnesses and fecal contamination of produce fields is a recognized food safety risk
The most sensitive optical techniques rely on detecting fluorescence responses of materials in feces to UV or violet illumination
The low quantum yields of fluorescence responses means that the responses are generally masked by ambient illumination

Summary

Introduction

Pathogens of fecal origin are the cause of most food-borne illnesses and fecal contamination of produce fields is a recognized food safety risk. An accepted practice is to survey fields for fecal contamination and signs of animal intrusion. Our laboratory has developed a number of optical techniques with the goal of augmenting such surveys. The most sensitive optical techniques rely on detecting fluorescence responses of materials in feces to UV or violet illumination. The low quantum yields of fluorescence responses means that the responses are generally masked by ambient illumination. The purpose of this study was to investigate the possibility of using a shroud to mitigate solar illumination and thereby facilitate detection of fluorescence responses using relatively inexpensive optical instrumentation

Objectives

Methods

Results