PORTABLE MULTISPECTRAL FLUORESCENCE IMAGING SYSTEM FOR FOOD SAFETY APPLICATIONS

Authors: Lefcourt, Alan; Kim, Moon; Chen, Yud

Submitted to: Proceedings of SPIE
Publication Type: Proceedings
Publication Acceptance Date: 10/29/2003
Publication Date: 12/1/2003
Citation: Lefcourt, A.M., Kim, M.S., Chen, Y.R. 2003. Portable multispectral fluorescence imaging system for food safety applications. SPIE Proceedings entitled: Monitoring Food, Safety, Agriculture, and Plant Health. 5271:62-72.

Interpretive Summary: Feces are known to be primary sources of disease causing microorganisms, and fecal contamination of foods can cause illness or death. Animal feces contains chemical compounds such as chlorophyll that can be detected by the fluorescent responses of these compounds to ultraviolet light. This paper describes a transportable fluorescence-imaging system for use in food safety applications. The system consists primarily of a ultraviolet light source, a light-intensifying camera with a six-position filter wheel, and computer software for controlling the system and automatically analyzing the resulting images. The hardiness of the system was demonstrated when the system was used successfully at a public field day to image apples artificially contaminated with dairy feces. The contamination sites were easily identified using automated detection methods. In addition, it is known that fecal contamination sites on apples can be identified using fluorescence imaging even after the apples are washed. By applying feces to apples and washing some of apples at hourly intervals, it was determined that five h was the minimum contact time that allowed identification of the contamination site after the apples were washed. This system can be used to study the effectiveness of apple washing systems. The technology may also provide a basis for developing tools to monitor the cleanliness of food preparation areas.

Technical Abstract: Fluorescence can be a sensitive method for detecting food contaminants. Of particular interest is detection of fecal contamination as feces is the source of many pathogenic organisms. Feces generally contain chlorophyll a and related compounds due to ingestion of plant materials, and these compounds can readily be detected using fluorescence techniques. Described is a fluorescence-imaging system consisting primarily of a UV light source, an intensified camera with a six-position filter wheel, and software for controlling the system and automatically analyzing the resulting images. To validate the system, orchard apples artificially contaminated with dairy feces were used in a "hands-on" public demonstration. The contamination sites were easily identified using automated edge detection and threshold detection algorithms. In addition, by applying feces to apples and then washing sets of apples at hourly intervals, it was determined that five h was the minimum contact time that allowed identification of the contamination site after the apples were washed. There are many potential uses for this system, including studying the efficacy of apple washing systems.