Detection of fecal contamination on cantaloupes using hyperspectral fluorescence imagery

• Published in: Journal of food science Vol. 70; no. 8; pp. e471 - e476
• Main Authors: Vargas, A.M, Kim, M.S, Tao, Y, Lefcourt, A.M, Chen, Y.R, Luo, Y, Song, Y, Buchanan, R
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.10.2005; Institute of Food Technologists; Wiley Subscription Services, Inc
• Subjects: Biological and medical sciences; cantaloupe; cantaloupes; classification; Contamination; detection; fecal contamination; Feces; Fluorescence; food contamination; Food industries; frequency; Fruit and vegetable industries; Fruits; Fundamental and applied biological sciences. Psychology; General aspects; hyperspectral imagery; hyperspectral imaging; Methods of analysis, processing and quality control, regulation, standards; ratio image; Scientific imaging; ultraviolet radiation; wavelengths; Fruit; Cucurbitaceae; Fluorescence; Imagery; Contamination; fecal contamination; Analysis method; ratio image; Dicotyledones; Angiospermae; Spermatophyta; Control method; Ratio; Cucumis melo; Feces; Detection; hyperspectral imaging; Melon; cantaloupe
• ISSN: 0022-1147; 1750-3841
• DOI: 10.1111/j.1365-2621.2005.tb11517.x

To determine whether detection of fecal contamination on cantaloupes is possible using fluorescence imaging, hyperspectral images of cantaloupes artificially contaminated with a range of diluted bovine feces were acquired from 425 to 774 nm in responses to ultraviolet-A (320 to 400 nm) excitation. Evaluation of images at emission peak wavelengths indicated that 675 nm exhibited the greatest contrast between feces contaminated and untreated surface areas. Two-band ratios compared with the single-band images enhanced the contrast between the feces contaminated spots and untreated cantaloupe surfaces. The 595/655-nm, 655/520-nm, and 555/655-nm ratio images provided relatively high detection rates ranging from 79% to 96% across all feces dilutions. However, both single band and ratio methods showed a number of false positives caused by such features as scarred tissues on cantaloupes. Principal component analysis (PCA) was performed using the entire hyperspectral images data; 2nd and 5th principal component (PC) image exhibited differential responses between feces spots and false positives. The combined use of the 2 PC images demonstrated the detection of feces spots (for example, minimum level of 16-microgram/mL dry fecal matter) with minimal false positives. Based on the PC weighing coefficients, the dominant wavelengths were 465, 487, 531, 607, 643, and 688 nm. This research demonstrated the potential of multispectral-based fluorescence imaging for online applications for detection of fecal contamination on cantaloupes.