SOFT WHITE WINTER-WHEAT KERNEL SEPARATION BY PERCENT PROTEIN

Eighty-five percent or more of the soft white wheat grown in the Pacif ic Northwest (PNW) is exported. About half of this wheat is sold to Pa cific Rim countries that require wheat with high test weight and less than 10.5% grain protein for making products such as packet breads, co okies, and sponge cakes. Soft white wheat grown in the PNW varies from less than 7 to over 14% grain protein content and has test weights ra nging from less than 700 to over 800 kg/m(3). This research was conduc ted to evaluate using a gravity table to separate soft white wheat on grain protein. Eight lots of soft white wheat, grown in Oregon, Idaho, and Washington under different cultural practices, were each separate d with a gravity table into nine categories representing gravity table discharge position. The gravity table separated wheat based on kernel weight. The r(2) for linear regression of gravity table discharge pos ition and kernel weight ranged from 0.92 to 0.98. This technique will not work in most cases for soft white winter wheat produced under irri gation because there is low correlation between kernel weight and prot ein percent. Most dryland produced wheat had a high negative correlati on between kernel weight and grain protein percent (correlation coeffi cients ranged from 0.98 to 0.99). Consequently, any method that separa tes soft white wheat containing light-high protein kernels on kernel w eight will also separate the wheat on grain protein.