Studies on Ground Corn Flowability as Affected by Particle Size and Moisture Content

Abstract. Corn is the primary feed grain in the U.S., and it accounts for more than 90 percent of total feed grain production and use. Besides this, corn is the primary input for the U.S. ethanol industry. This results in tremendous infrastructure for handling and storage of corn and byproducts throughout the year. The flow properties of ground corn, which is a principal ingredient of animal feed, are very complex in nature. Many physical and chemical properties viz. angle of repose, bulk density, moisture of the product, protein content in the surface layer, etc. affects the flow properties of corn and its products. Flow through a hopper is a typical example of complex flow. Bridging or caking of feed material in feed hoppers are common problems, and many times blocks the flow completely leaving animals without feed. Daily changes in temperature and relative humidity affect the equilibrium moisture content of feed. Size of corn particles affect angle of repose, bulk density and cohesive forces between particles, and thus flow characteristics of the feed. In this study, flow characteristics of ground corn were examined as functions of particle size and moisture content. Feed utilization was historically maximum (i.e. minimum ratio of feed consumption to weight gain), when mean particle size diameter is about 822 microns for roller milled corn flour. In recent times, livestock producers have found that feed efficiency can increase as particle size decreases. Furthermore, excess moisture makes flour sticky and hampers free sliding of particles over each other during flow. Keeping this in view, different combinations of particle sizes and product moisture content were studied with the objectives of understanding and enhancing corn flour flowability.