Cereal Chem 60:344 - 350.  |  VIEW ARTICLE
Kernel Hardness of Some U.S. Wheats.

W. T. Yamazaki and J. R. Donelson. Copyright 1983 by the American Association of Cereal Chemists, Inc. 

Pure variety wheat samples grown over a 21-year period at locations in the eastern United States generally showed no significant correlation between particle size index (PSI) and protein content. Grain moisture content was found to exert a considerable effect on PSI. In a given wheat sample, higher moisture content was associated with greater softness as determined by our PSI test procedure. In making comparisons of hardness, an adjustment to a uniform moisture content may be made by reference to a fan-shaped family of regression lines developed under specific conditions prevailing for PSI determinations. Particle size index values appear to have greater value when they can be associated with a milling characteristic such as break flour yield rather than standing alone. PSI values obtained by grinding the wheat samples through a properly calibrated burr-type grinder correlated significantly with break-flour yield from Allis-Chalmers laboratory millings, whereas PSI data using a comminution grinder were not correlated with milling data.