| There are abundant soybean resources in China. Soybean's yield is near upon 15,000,000 tons every year, accounting for the fourth of the world's one. Soybean has more protein, lipid, amino acid, fatty acid and lecithin than other crops, supplying high quality food for human and high energy, high protein feed for animals. In recent years, along with the development of the stockbreeding in China, demand for protein is increasing continuously. Nevertheless protein resources from animals is limited, which can't meet the need of the feeding industry, the protein resources must be founded to party replace ones from animals. Soybean protein from the plants has particular advantage. Extruded soybean can replace traditional method of bean cake and lipid, when it is added to feed. The method obtains preferable breed effect.Now, technology of extruding soybean is perfected gradually. But, extruder mostly has complicated structure, large size, high price. It is difficult to manipulate and can't satisfy the need of individual user and small enterprise. A small reformative extruder is designed for experiment, which has simple structure, low price, and is easy to operate and maintain. The small extruder that is used to process soybean will promote exploitation and utilization of the soybean resources.In order to study the technology of extruding soybean deeply and improve the performance of extrusion experimental equipment, the working principle of extruder is analyzed in this paper. The mechanism of extruding soybean is also preliminarily discussed. On the basis of present equipment, a kind of single-screw extruder is used in this experiment. The main working parts are designed and studied. The factors influence extrusion effect are analyzed synthetically. Soybean moisture content, screw speed, extruding temperature and clearance are different factors. The effect of these factors on extrudingprocession is studied through four single factor experiments in which test indexes are productivity and output per kWh. It provides gist for quadratic regressive orthogonal rotatory experiment.Regression equations for extruding criteria are established though three-factor with five-level quadratic regressive orthogonal rotatory experiments. The effects of soybean moisture content, strew speed, extruding temperature on productivity, output per kWh and extruding pressure are discussed. By establishing a mathematical model, the influences of primary factors which affect the extruding criteria have been analyzed with curve surface function. Finally, the technologic parameters have been optimized by the optimization theory using nonlinear programming method. A group of optimum parameters are confirmed.Aimed at resolving the problems in the experiment, on the basis of analysis and calculation, optimal design of structural and processing parameters of extruder are completed with the help of the software. It provided the theoretic guidance for reformative design of the machine.Finally, the application of extruded production is discussed.From experimental study following conclusions are made.(1) Nutrition composition contrast analysis of soybean and extruded soybean indicate that the crude protein content of extruded soybean increases 2.69%, the ash increases 7.45%, the crude fat doesn't decrease on the whole; the crude fiber decreases 29.11%, the activity of urease decreases 69.03%. Results show that the nutrition composition of extruded soybean has been changed, which is advantageous to growth of the animals.(2) Extruded soybean is tiny particles form, with many tiny bore, and golden color. The oil is exposed on the surface of extruded soybean. Microstructure of extruded soybean which can be observed with the help the electron microscope, indicates that the cell structure of soybean is destroyed, laniated to floccular fiber, distance of cell is increased, lipocyte is broken and lipid is released. It is easy for animals to digest and imbibe lipid.(3) Through single factor experiment and quadratic regressive orthogona...
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