Grain color stability and classification of hard white wheat in the US

Variability in grain color of hard white wheat was investigated in cultivars grown over two years in Nebraska and Kansas and related to variation observed in grain hardness, kernel weight, kernel size, and protein content and to color of ground meal and flour. Grain color was scored subjectively, through visual evaluation, and objectively through use of a colorimeter. Of the 543 hard white wheat samples examined by USDA-GIPSA grain inspectors, 15.5% were scored as visually darker than the 1990 grain color standard established as a minimum for hard white wheat classification. The remaining samples were scored as having grain color essentially equal (28.2%), or visually 'whiter' (56.4%), than the color standard. Distributions of colorimeter L, a, and b values suggest that the colorimeter had difficulty in capturing the subtleties of visual ratings. There were significant decreases in kernel hardness and grain protein content among samples that scored visually 'whiter' than the color standard. Grain color, measured either visually or by colorimeter, was not a reliable indicator of either ground meal color or flour color. As such, it may provide little indication of grain quality, end-product color, or processing value to the milling and baking industries.