A method of producing gluten-free oats from a supply of grains incorporating oats and at least one contaminant grain includes hyperspectral imaging and analyzing data of only a particular region of interest of each grain in the supply of grains, particularly excluding tip and peripheral edge regions of the grain. Therefore, the particular regions of interest is limited to a central region of each grain determined by locating a centroid of the grain and collecting data of the grain from only pixels in a predetermined spacing from the centroid. Preferably, the hyperspectral imaging is only performed in wavelengths ranging from 1000 to 2500 nm. The method can be particularly employed in connection with quality control sampling of a pre-sorted supply of gluten-free oats to assure a gluten level well below 20 ppm, preferably a gluten level of no greater than 10 ppm.