Detecting Contamination in Whole Corn Ears Infected with Toxigenic Aspergillus Flavus Using Fluorescence Hyperspectral Imaging

Hruska, Z., Yao, H., Kincaid, R., Brown, R. L., Cleveland, T. E., & Bhatnagar, D. (2012). Detecting Contamination in Whole Corn Ears Infected with Toxigenic Aspergillus Flavus Using Fluorescence Hyperspectral Imaging. Abstracts of lectures and posters of the WMF meets IUPAC 2012 Conference. Rotterdam, the Netherlands: WMFmeetsIUPAC2012.

Abstract

Aflatoxin is a naturally occurring toxin in food and feed crops, predominantly produced by toxigenic fungi Aspergillus flavus and Aspergillus parasiticus. Because of its potent carcinogenic properties, aflatoxin is of major concern to the food and feed producers around the world. Rapid and non-invasive detection methods to address this problem would be valuable tools for food and feed producers worldwide. Imaging methods including fluorescence hyperspectral and multispectral imaging have proven to have value in food safety applications. The current study assessed the severity of aflatoxin contamination in whole corn ears from a cornfield inoculated with spores from two different strains of Aspergillus flavus (A. flavus) as well as aflatoxin production in corn ears from the same field due to natural infestation with the aid of a fluorescence hyperspectral system. A small corn plot provided by the LSUAg Center, in Baton Rouge, Louisiana, USA was used during the 2008-growing season. Two groups of four hundred plants were inoculated with inoculums from two different strains of toxigenic A. flavus (AF-13 and NRRL-3357), both shown to be robust aflatoxin producers. One group of four hundred plants was designated as controls. Any contamination detected in the controls was attributed to natural infestation. A subset of each group was imaged with a VNIR hyperspectral system under UV excitation and subsequently chemically analyzed using affinity column fluorometry. Harvested corn ears were shucked, shelled and stored in plastic bags (1 bag/ear). Contents of each bag were split into 6-7 trays for imaging because of field of view constraints of the hyperspectral sensor. Kernels were imaged in a single layer under a UV light source with excitation wavelength centered at 365 nm. Regions of interest were created for each tray 1) separating corn from background and 2) isolating all contaminated pixels. After imaging all trays were pooled into one sample/ear and processed for chemical analysis. Group differences were statistically analyzed. Results from this study may provide useful information for developing rapid, non-invasive instrumentation and/or methodology for whole ear inspection.