|Mcmullen, Michael - NORTH DAKOTA STATE UNIV|
Submitted to: American Association of Cereal Chemists Meetings
Publication Type: Abstract Only
Publication Acceptance Date: May 9, 2006
Publication Date: September 21, 2006
Citation: Doehlert, D.C., Mcmullen, M.S. 2006. Oat kernel density and the physical basis of test weight [abstract]. American Association of Cereal Chemists Meetings. World Grain Summit Program Book, P. 71. Technical Abstract: Test weight or bulk density of oats (Avena sativa L.) has a major influence on the value of oat grain yet little is known about the physical basis for test weight in oats. Test weight can be attributed to a combination of kernel density and packing efficiency. We have measured oat kernel volume and density by a sand displacement, and thus derived the packing factor for six oat cultivars grown in three environments. Kernel volumes ranged from 31 to 38 mm3, were highly correlated with kernel mass. Kernel densities ranged from 0.96 to 1.03 g/cm3. Packing efficiency, which is defined as the percentage of the volume of a container occupied by the grain, ranged from 53 to 55%. Both values exhibited genotypic and environmental variation. Regression analysis suggested that 78% of the variation in test weight could be attributed to kernel density and most of the remaining variation could be attributed to the packing efficiency. Size fractionation of grain by sieving and size analysis by digital image analysis indicated that smaller kernels packed more efficiently than larger kernels within an oat sample, and larger kernels in a sample were less dense than the smaller kernels. Analysis of oat kernel components indicated groat densities were about 1.3 g/cm3 and hull densities were about 0.7 g/cm3, with very little genotypic variation in these traits. However, the sum of groat and hull volumes were consistently less than that of whole kernels, suggesting the presence of empty space within the hulls, which could profoundly affect test weight. The difference in densities of groat and hull provide the physical basis for the recognized relationship between groat percentage and test weight.