Grain color stability and classification of hard white wheat in the U.S.

Abstract

Variability in grain color of hard white wheat was investigated incultivars grown over two years in Nebraska and Kansas and related tovariation observed in grain hardness, kernel weight, kernel size, and proteincontent and to color of ground meal and flour. Grain color was scoredsubjectively, through visual evaluation, and objectively through use of acolorimeter. Of the 543 hard white wheat samples examined byUSDA-GIPSA grain inspectors, 15.5% were scored as visually darker thanthe 1990 grain color standard established as a minimum for hard whitewheat classification. The remaining samples were scored as having graincolor essentially equal (28.2%), or visually `whiter' (56.4%), than thecolor standard. Distributions of colorimeter L, a, and b values suggest thatthe colorimeter had difficulty in capturing the subtleties of visual ratings.There were significant decreases in kernel hardness and grain proteincontent among samples that scored visually `whiter' than the colorstandard. Grain color, measured either visually or by colorimeter, was nota reliable indicator of either ground meal color or flour color. As such, itmay provide little indication of grain quality, end-product color, orprocessing value to the milling and baking industries.