Influence of kernel shape and size on the packing ratio and compressibility of hard red winter wheat

Authors: PETINGCO, MARVIN - Kansas State University; Casada, Mark; MAGHIRANG, RONALDO - Kansas State University; THOMPSON, SIDNEY - University Of Georgia; MCNEILL, SAMUEL - University Of Kentucky; MONTROSS, MICHAEL - University Of Kentucky; TURNER, AARON - University Of Kentucky

Submitted to: Transactions of the ASABE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/15/2018
Publication Date: 6/1/2018
Citation: Petingco, M.C., Casada, M.E., Maghirang, R.G., Thompson, S.A., McNeill, S.G., Montross, M.D., Turner, A.P. 2018. Influence of kernel shape and size on the packing ratio and compressibility of hard red winter wheat. Transactions of the ASABE. 61(4):1437-1448. https://doi.org/10.13031/trans.12648.
DOI: https://doi.org/10.13031/trans.12648

Interpretive Summary: Grain compaction naturally occurs during bin storage due to overbearing pressure of the grain. The magnitude of the compaction must be known to estimate grain mass for inventory and auditing purposes. Estimation of compaction from a theoretical basis is hampered by a lack of fundamental understanding of the effect of particle shape and size. We evaluated the effect of shape and size of wheat kernels on packing density and compressibility for two hard red winter (HRW) wheat cultivars. We found that packing density generally increased and compressibility decreased with larger kernel size, larger kernel sphericity, and greater flatness shape factor. The more spherical, less elongated and less round the kernels, the higher its packing density and the lower its compressibility. With the mixtures of different sized kernels, the higher the percentage of larger kernels in a mixture, the higher was its packing density and the lower its compressibility. Two varieties of wheat were evaluated, but did not differ in compressibility and packing factor. This information provides the basis for theoretical predictions of compressibility based on kernel properties.

Technical Abstract: Grain compaction occurs during bin storage and its determination is important for grain mass estimation needed for inventory and auditing. The degree of compaction is dependent on grain type, bin type, moisture content, amount of grain, initial grain bulk density, and variation in kernel size. Previous studies have correlated several of these parameters such as bulk density and grain packing with moisture content. This study investigated the influence of wheat kernel shape and size distribution on packing density and compressibility. Two dockage- and shrunken and broken- free hard red winter (HRW) wheat samples were sieved using US Tyler sieves #6, #7, #8, and #10, and those retained in the sieves were used in the experiments. The kernel dimensional parameters and bulk sample parameters were measured and additional derived parameters were calculated for each size fraction and variety. Packing density and compressibility of the size fractions and of binary and ternary mixtures of the size fractions were also determined for each variety. Packing density increased with larger kernel size while compressibility decreased. Sphericity and flatness shape factor had strong positive linear relationships with packing density and strong negative relationship with compressibility, while elongation shape factor behaved the opposite way with packing density and compressibility. The higher the percentage mass of the larger kernel fraction in a mixture, the higher was its packing density and the lower its compressibility. The two varieties did not significantly differ in packing density and compressibility. These findings can be used in developing a model for more accurate estimate of grain pack factor and determination of mass of grain inside bins and other storage structures.