Analysis on forming process of extruded corn as feed material affected by thermal condition

Abstract.

In the modern feed industry, after crushing, conditioning, granulating and cooling section, a variety of raw materials are processed into pellet feed in accordance with certain objectives. By mechanical compression and method of forced through a die orifice polymerization molding, pellet feed are obtained with advantages such as avoid picky eaters of feeding animal etc., which has become the main feed products application form. The pelleting processing has showed significant impact on final quality of pellet as well as the breeding process. Recently, the promotion of extrusion technology brings new opportunity and method for the comprehensive utilization of corn. After the extrusion technology, the nutrient content and structure of starch of corn changed in a significance degree; followed the cleavage of intermolecular bond in starch, cut of starch chain and fully gelatinization of starch make corn obtain well water-solubility bring with better dissolution, absorption and digestion. Therefore, extruded corn is widely used in high-grade feed or piglets feed since its advantage of promote the utilization value of corn as main energy feed. However, after extrusion process, complicated diversifications are happened which cause the variety between extrusion corn and regular corn and the research concerned about the performance of these variety in forming process of pellet feed should be paid more attention. Particularly, the influence of thermal condition in pelleting process of extrusion corn needs more study, as a thermal sensitive material. In this view, as the subject of this article, mash extrusion corn is conducted several compression trails using self-designed forming apparatus which is loaded on an electronic universal testing machine basing on actual pelleting processing parameters(including warm-up time, ground particle size, moisture content, compression pressure, etc.). As for the primary investigating factor, the test levels of environmental temperatures are designed as followed: 60℃, 70℃, 75℃, 80℃, 85℃, 90℃, according to the apply occasions of extrusion corn compression. After the compression stage with pressure-deformation data collected in certain frequency, several quality indexes for pellet feed are measured including pellet hardness, powder content ratio and density while the specific energy consumption is calculated by the trail data. Basing on test results above, the situation of particle size distribution of extrude corn is analyzed; also there is a discussion about the influence law of various heating temperatures on quality indexes of pellet, thus provide optimal temperature for particular index and best processing condition considering the specific energy consumption outcome. In the line with the pressure-deformation data from compression test, particular forming curves of extrude corn for different thermal condition are obtained and discussed in the idea of separate & fit method which help the distinguish study of specificity of each part for its unique properties. By the result of this article, theory reference and fundamental data of extrude corn‘s changing law in compression forming process of pellet feed as a thermal-sensitivity material are provided as well as the influence of thermal condition on the quality of pellet production, which could be profound benefited and make contribution towards better utilization of this feed source in the very industry.