Powdered soybean processing is a process in which soybeans are used as raw materials, which are peeled and pulverized to obtain a powdery product. Powdered soybean is raw soy flour, which can be divided into full-fat and defatted. Generally, it is full-fat soy flour, commonly used raw materials for making soymilk, bean curd and tofu.
The soybeans with full grains and high protein content are first cleaned, and the sundries are removed, and then dried. The purpose is to heat and evaporate the excess water in the soybeans, so that the water content of the soybeans is reduced to 8% to 10%, which is convenient to improve the soybean crushing effect. And make the bean skin and watercress easy to separate. In addition, due to the heat treatment, anti-nutrients in soybeans can be effectively inactivated, reducing the production of beany flavor. The drying temperature and time vary according to the requirements of the production process. Generally, the drying temperature is 95 ° C and the time is 2 hours. The commonly used drying equipment is a rotary baking machine or a fluidized bed dryer.
The dried soybeans can be peeled after being cooled for a period of time, so as to reduce the cellulose content in the instant soybean powder and improve the quality of the tofu powder. Dehulling is done by crushing and separating (see soymilk processing). The vertical steel mill is often used for crushing, so that the bean skin and the bean curd are separated, and then the fan is used for separation. The peeling rate of the peeling machine should be greater than 95%.
The purpose of pulverization is to further pulverize the separated watercress into fine particles. Commonly used pulverizers include micro-pulverizers and ultra-fine pulverizers such as screen type and airflow type. When processed with a sieveless pulverizer, the watercress enters the pulverizing chamber through the feeding chamber, and is hit by the hammer, and is broken by the shearing and friction of the tooth plate on the side of the pulverizing chamber. The pulverized material is discharged along the axial direction under the action of the negative pressure of the fan, and is supplemented and pulverized when it passes through the control wheel. The particle size of the finished product is controlled by adjusting the gap between the control wheel and the bushing. The thickness of powdered soybean should reach 400 meshes per inch, and those of about 8-14 microns should be above 92%. The finished powdered soybean can be obtained after the cyclone powder is dried and collected. The protein content of soybean meal should be greater than 38%, and about 0.85 kg of soybean meal can be produced per kilogram of soybeans.
The raw materials of defatted soybean meal are mainly cold-pressed soybean cake and low-denaturation leached soybean meal. In the production, the soybean protein is denatured as little as possible, and the production process is also very simple. The defatted soybean meal is crushed, classified and packaged to obtain the finished product. Defatted powdered soybean can be used as a food raw material to be mixed with flour to make bread, snacks, fried food, sausages, etc. If it is eaten directly, it should be subjected to moist heat treatment in advance to remove the beany smell and harmful ingredients. Low-denaturation defatted powdered soybean can be further prepared into soybean milk powder, protein concentrate, protein isolate, tissue protein, etc. due to its small thermal denaturation and high NSI and PDI values.