Evaluating the Relationship Between Aflatoxin Concentration and Hyperspectral Fluorescence Response in Single Corn Kernels

Hruska, Z., Yao, H., Kincaid, R., Brown, R., Cleveland, T., & Bhatnagar, D. (2009). Evaluating the Relationship Between Aflatoxin Concentration and Hyperspectral Fluorescence Response in Single Corn Kernels. ISM Conference 2009 Proceedings. Tulln, Austria: International Society for Mycotoxicology.

Abstract

The objective of the present study was to take advantage of the UV elicited response of corn kernels contaminated with Aspergillus flavus expressed under 365 nm UV excitation and assess the response measured with a hyperspectral fluorescence imaging sensor for possible quantification of aflatoxin, using statistical models. Infected corn samples were harvested from a cornfield in Tifton, GA. Kernels exhibiting fluorescence were identified under UV light source with excitation wavelength centered at 365 nm, and extracted. Several adjacent, non-glowing kernels from the same ear were also extracted and used as controls. Only whole, undamaged kernels were imaged using hyperspectral fluorescence imaging sensor. Fluorescence hyperspectral signatures and statistical information were extracted from each kernel. After imaging, each corn kernel was crushed and weighed. Each sample was extracted with methanol/water (80/20%). Extracted samples were diluted and passed through AflaTest affinity columns. Samples were eluted with pure methanol and measured with a fluorometer from VICAM. Fluorescence emission spectrum in the visible near infrared region was correlated with aflatoxin content of each corn kernel across all wavelengths between 400 and 600 nm. A weak negative correlation of the two measures was noted between 400 and 450 nm with r = -0.67. Multiple linear regression model across all 74 fluorescence spectral bands was used to predict aflatoxin content based on spectral information. When the non-positive estimates were assigned to zero by the model, the Coefficient of Determination r2 = 0.72. Our results illustrate the potential of using fluorescence hyperspectral curves for estimating aflatoxin content in individual corn kernels.