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Single Wheat Kernel Size Effects on Near-Infrared Reflectance Spectra and Color Classification

¹Grain Marketing and Production Research Center, USDA-ARS, Manhattan, KS 66502. Mention of a trademark or proprietary product does not constitute a guarantee or warranty of the product by the U.S. Department of Agriculture and does not imply its approval to the exclusion of other products that also may be suitable. ²Corresponding author. Phone: 785/776-2753. Fax: 785/776-2792. E-mail: fdowell@usgmrl.ksu.edu ³Agricultural Engineering Department, Texas A&M University, College Station TX 77843-2117.

An optical radiation measurement system was used to measure reflectance spectra of single wheat kernels from 400 to 2,000 nm. Five classes of wheat were used for this study. Three kernel sizes (large, medium, and small) were used to determine how wheat kernel size affects visible and near-infrared (NIR) reflectance spectra and single wheat kernel color classification. Mean kernel weights ranged from 35.6 to 57.2 mg for large kernels, from 26.9 to 45.0 mg for medium kernels, and from 17.6 to 31.4 mg for small kernels. The results showed that wheat kernel size significantly affects visible and NIR reflectance spectra. Determination of the color class of red kernels increased in accuracy and that of white kernels decreased in accuracy as kernel size decreased. Data pretreatments such as multiplicative scatter correction (MSC), first or second derivatives, and first or second derivatives with MSC reduced the effect of kernel size on reflectance spectra and color classification.