Effect of Moisture Content and Particle Size on Physical and Pasting Properties of Corn Meal

Abstract

<abstract> <bold>Abstract.</bold> The study was conducted to determine the physical and pasting properties of corn meal used for feed ingredients. Corn meal of three particle size, geometric mean particle diameters are respectively 217, 363 and 486 μm, at the wet basis moisture content of 7%, 10%, 13%, 16% and 19%, were selected to study the physical and pasting properties using standard methods, respectively. Friction parameters included the angle of internal friction, angle of sliding friction and angle of repose of different wet basis moisture content and different particle size. The friction parameters of corn meal were measured by direct shear apparatus, self-made bevel instrument and the angle of repose for measuring device, respectively. To study the variation of gelatinization for the material during processing, rapid viscosity analysis (RVA) were performed to research the pasting properties of the materials, then analyzed the variation of testing results. Angle of internal friction increased (from 25.32° to 34.07°) with decrease in the particle size of the meal and increase in moisture content. The angle of sliding friction of the corn meal were found to be from 22.8° to 49.8°, 25.7° to 51.6°, 34.2° to 54.7°, 37.4° to 60.7°, respectively for stainless steel, galvanized plate, glass and plastic board surfaces. The angle of friction increased with the increase of moisture content and the decrease of particle size. The pasting properties increased with the decease of decrease of particle size. This study could provide useful data for the physicochemical characteristics of corn meal, and to design processing machine in related equipment in feed industry.