Skip to main content
ARS Home » Northeast Area » Beltsville, Maryland (BARC) » Beltsville Agricultural Research Center » Environmental Microbial & Food Safety Laboratory » Research » Publications at this Location » Publication #321099

Title: Hyperspectral fluorescence imaging using violet LEDs as excitation sources for fecal matter contaminate identification on spinach leaves

Author
item EVERARD, COLM - University Of Dublin
item Kim, Moon
item CHO, HYUNJEONG - Rural Development Administration - Korea
item O’DONNELL, COLM - University Of Dublin

Submitted to: Journal of Food Measurement & Characterization
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/3/2015
Publication Date: 1/1/2016
Citation: Everard, C., Kim, M.S., Cho, H., O’Donnell, C. 2016. Hyperspectral fluorescence imaging using violet LEDs as excitation sources for fecal matter contaminate identification on spinach leaves. Journal of Food Measurement & Characterization. 10(1):56-63.

Interpretive Summary: Food safety in the production of fresh produce for human consumption is a worldwide issue and needs to be addressed to decrease foodborne illnesses and resulting costs. In this study, we evaluated the use of hyperspectral fluorescence imaging coupled with image analysis techniques for detection of animal fecal contaminates on spinach leaves. Fluorescence emission profiles of spinach leaves were monitored over a 27 day storage period; peak emission blue-shifts were observed over the storage period accompanying a colour change from green to a green-yellow-brown hue. A wavelength ratio technique using four wavebands (680, 688, 703 and 723 nm) was successful in identifying 100% of fecal contaminations on both fresh and non-fresh leaves. An on-line fluorescence imaging inspection system for fecal contaminant detection has potential to allow fresh produce producers to reduce foodborne illnesses and prevent against the associated economic losses. The findings presented is this investigation is informative to agricultural engineers who are developing fresh produce safety inspection technologies.

Technical Abstract: Food safety in the production of fresh produce for human consumption is a worldwide issue and needs to be addressed to decrease foodborne illnesses and resulting costs. Hyperspectral fluorescence imaging coupled with multivariate image analysis techniques for detection of fecal contaminates on spinach leaves (Spinacia oleracea) was evaluated. Violet fluorescence excitation was provided at 405 nm and light emission was recorded from 464 to 800 nm. Partial least square discriminant analysis and wavelength ratio methods were compared for detection accuracy for fecal contamination. Fluorescence emission profiles of spinach leaves were monitored over a 27 day storage period; peak emission blue-shifts were observed over the storage period accompanying a colour change for green to green-yellow-brown hue. The PLSDA model developed correctly detected fecal contamination on 100% of relatively fresh green spinach leaves used in this investigation, which also had soil contamination. The PLSDA model had 19% false positives for non-fresh post storage leaves. A wavelength ratio technique using four wavebands (680, 688, 703 and 723 nm) was successful in identifying 100% of fecal contaminations on both fresh and non-fresh leaves. An on-line fluorescence imaging inspection system for fecal contaminant detection has potential to allow fresh produce producers to reduce foodborne illnesses and prevent against the associated economic losses.