Submitted to: Cereal Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/31/2009
Publication Date: 12/10/2009
Citation: Doehlert, D.C., Wiesenborn, D.L., Mcmullen, M.S., Ohm, J., Riveland, N.R. 2009. Effects of Impact Dehuller Rotor Speed on Dehulling Characteristics of Diverse Oat Genotypes Grown in Different Environments. Cereal Chemistry. 86(6): 653-660 Interpretive Summary: Oat grain is usually covered with a papery hull that must be removed before the oat can be processed for human consumption. Oats are usually dehulled with an impact dehuller, where grain is fed into a spinning rotor and the rotor expels the grain against the wall of the dehuller. The force of the impact breaks the hull from the groat, which is the meaty part of the oat. Hulls are removed by aspiration. We have measured the effects of different rotor speeds on dehulling characteristics of different oat cultivars grown in different environments. We call the proportion of kernels that get dehulled during a single pass through the dehuller the dehulling efficiency. We find that dehulling efficiency increased with rotor speed with all varieties, but more groats were broken at higher rotor speeds, so to optimize yield of whole groats, the rotor speed must be adjusted to a speed which differs for all batches of oats. We have also found that oats grown in hot dry environments break more than those grown in cooler wet environments. At this point, we are not sure if the hot, dry weather makes kernels more brittle, or wet, cool weather makes kernels stronger.
Technical Abstract: Commercial processing of oats for human consumption generally requires impact dehulling to isolate groats from the hull. Impact dehulling involves feeding oat grain into the center of a spinning rotor that expels the grain against the walls of the dehuller. The force of the impact breaks the hull from the groat. We have tested the effect of rotor speed on dehulling efficiency, groat breakage and unbroken groat yield on eighteen oat genotypes from replicated plots in six different environments. Dehulling efficiency and groat breakage increased with rotor speed with all genotypes and environments, but there were significant genotypic and environmental effects as well. In general, genotypes with higher test weight and kernel density dehulled more efficiently at slower rotor speeds. Oat genotypes with higher oil and protein concentrations in their groats tended to break less during dehulling. Oats from hotter, drier environments suffered greater groat breakage. Maximal unbroken groat yield represented a balance between dehulling efficiency and groat breakage, but groat proportion and dehulling efficiency appeared to be the most important factors contributing to groat yield.