Classification of Scab and Other Molddamaged Wheat Kernels by Nearinfrared Reflectance Spectroscopy

Scab (Fusarium head blight) is a disease that causes wheat kernels to be shriveled, underweight, and difficult tomill. Scab is also a health concern because of the possible concomitant production of the mycotoxin deoxynivalenol. Currentofficial inspection procedures entail manual human inspection. A study was undertaken to explore the possibility of detectingscabdamaged wheat kernels by a nearinfrared (NIR) diode array spectrometer. Wheat kernels from three categories (sound,scabdamaged, and molddamaged) were visually inspected by and furnished by the USDA Grain Inspection, Packers, andStockyards Administration (GIPSA). The reflectance spectrum of each intact kernel was collected at 6nm increments overa 940 to 1700 nm region. Exhaustive searches of the best combination of individual wavelengths, best difference ofwavelengths, best ratio, and combinations thereof were performed on a set of 100 kernels from each of the three categories.The best modeling classification occurred for precisely aligned kernels using a combination of kernel mass and the differencein log(1/R) at two wavelengths, 1182 and 1242 nm. When applied to a test set, the classification model correctly identifiedthe intended category with 95% accuracy. The most difficult to classify conditions were scabdamaged vs. molddamagedand molddamaged vs. sound. When scabdamaged and molddamaged kernels were combined into one category, the overallaccuracy for a twocategory (sound vs. damaged) classification model was between 95% and 98%, depending on the kernelorientation scheme and inclusion of kernel mass. The achieved accuracy levels demonstrate the feasibility of using NIRreflectance spectroscopy with as few as two wavelengths to assist in wheat grading and commercial sorting.