Submitted to: American Association of Cereal Chemists Meetings
Publication Type: Abstract Only
Publication Acceptance Date: 6/10/2005
Publication Date: 9/21/2005
Citation: Doehlert, D.C., Wiesenborn, D. 2005. Interactions of kernel size and rotor speed in oat dehulling characteristics [abstract]. In: American Association of Cereal Chemists Annual Meeting Program Book. p. 193. Interpretive Summary:
Technical Abstract: Central to commercial oat processing is impact dehulling. During impact dehulling, oats are fed into a spinning rotor that expels the kernels against an impact ring. The force of the impact frees the groat from the hulls. In this study we have examined the effects of kernel size and rotor speed on dehulling characteristics using an impact dehuller. We separated kernels of three cultivars (AC Assiniboia, Gem, and Brawn) according to size by sieve separation (separation by width), disk separation (separation by length) and by gravity table (separation by density). Size was analyzed by thousand kernel weight, digital image analysis and test weight. Fifty-gram samples were adjusted to 9 percent moisture and dehulled at four different rotor speeds. Groat percentage, dehulling efficiency and groat breakage were measured after dehulling. We found that when kernels were separated by width, the larger sized kernels dehulled more efficiently at slower rotor speeds than did the smaller kernels. In sharp contrast, when kernels were separated by length, then the smaller kernels dehulled more efficiently at slower rotor speeds than did the larger kernels. The reason for this apparent contradiction is not yet clear, but was consistent for all cultivars tested. Groat percentage increased with decreasing kernel size and rotor speed. Groat breakage increased with rotor speed for all kernel sizes. Analysis of groat yield indicated that adjusting dehulling conditions according to kernel size improved yields over optimal dehulling conditions for unfractionated kernels. Data suggested that kernel mass is not necessarily the best criterion for size separation, and that linear measurements of kernel size may be more important in determining the optimal rotor speed for impact dehulling.