EFFECT OF WHEAT MOISTURE-CONTENT ON HARDNESS SCORES DETERMINED BY NEAR-INFRARED REFLECTANCE AND ON HARDNESS SCORE STANDARDIZATION

Near-infrared reflectance instrumentation provides an empirically meas ured scale for wheat hardness. The hardness scale is based on the radi ation-scattering properties of meal particles at 1,680 and 2,230 nm. H ard wheat meals usually have larger particle sizes than soft wheat mea ls. The objective of this study was to determine the sensitivity of ne ar-infrared reflectance wheat hardness measurements to moisture conten t, and to make the hardness score (HS) independent of moisture by corr ecting hardness measurements for the actual moisture content of measur ed samples. Forty wheat cultivars composed of hard red winter, hard re d spring, soft red winter, and soft white winter were used. Wheat kern el sample groups were stored at 20, 40, 60, and 80% rh. After equilibr ation, the samples were ground, and the meal was analyzed for HS and m oisture. Averaged across wheat samples and relative humidity treatment s, HS were 48, 50, 54, and 65 for 20, 40, 60, and 80% rh, respectively . HS from storage at 80% rh (13.4% meal moisture) were higher (P < 0.0 5), and HS from storage at 20% rh (9.3% meal moisture) were lower (P < 0.05) than the control values, which had an intermediate meal moistur e content (11%). Within each class of wheat, HS increased as moisture content increased. An algorithm was developed to correct HS to 11% moi sture. The correction provided HS that were nearly independent of mois ture content.