1. Selection of extrusion methods There are mainly two extrusion methods: dry extrusion and wet extrusion. Which one to choose depends on the actual situation. First of all, it depends on the function of the extruder you are using. At present, we are using Henan Sunshine Industrial high-efficiency extrusion extruder, which can be used for dry and wet extrusion. It should be determined according to the moisture content of soybeans. When soybeans have a lot of moisture, it is best to use dry puffing, which is conducive to the evaporation of water and reduces the moisture content of soybean flour. Wet puffing is mainly through the steam in the conditioner, and the clinker enters the puffing chamber, but the product after pressurized puffing has high moisture content and must be dried and cooled. When the moisture content of soybeans is low, wet puffing can be used, because adding steam is easy to temper, can increase the yield per unit time, has a stronger destructive effect on some anti-nutritional factors, and can further improve and improve soybean flour. nutritional value.

2. Adjustment of temperature and time The adjustment of puffing temperature and time is mainly based on the moisture content of soybeans. When the moisture content of soybeans is high, the quality of soybean flour meets the requirements. The method of aging is to increase the aging speed without adding steam. temperature, slow down the processing speed and prolong the post-curing time. We have explored in practice that when the soybean moisture is 14% to 16%, the processing temperature is gradually raised to 150-160°C for 6-7 minutes; if the soybean moisture is lower than 13.5%, the temperature can be lowered to 120-130°C ℃, the time is 5-6 minutes, the curing effect is better.

3. Inspection of maturity The maturity of raw soybeans is to effectively destroy some anti-nutritional factors, improve their utilization rate, and enable livestock and poultry to obtain better production performance after eating. But if it is overripe, it will cause the destruction of some amino acids. If the heating is excessive, the damage to lysine, arginine and cystine will be greater, and the digestibility of methionine, isoleucine and lysine will decrease, and the food intake will decrease. If the degree of ripening is not enough, some anti-nutritional factors in soybeans, such as trypsin inhibitors, lipoxygenase, urease, etc., cannot be effectively destroyed, seriously affecting its utilization rate, so the degree of ripening must be tested. In general, urease activity in soybean flour is measured to determine maturity. At present, there are many detection methods, among which the pH value addition method and the phenol red method are commonly used. my country's feed standard stipulates that the pH value of urease activity shall not exceed 0.4. Many studies have shown that the urease activity is only in the range of 0.03 to 0.4, and the feeding effect is the best. However, it is best to use the urea-phenol red qualitative method to detect the urease activity in the feed mill site. Therefore, the method is simple and fast, has a low technical level, is easy to master, and can also achieve the purpose of detection in production, and is suitable for popularization and use. The more commonly used methods are the pH value addition method and the phenol red method. my country's feed standard stipulates that the pH value of urease activity shall not exceed 0.4. Many studies have shown that the urease activity is only in the range of 0.03 to 0.4, and the feeding effect is the best. However, it is best to use the urea-phenol red qualitative method to detect the urease activity in the feed mill site. Therefore, the method is simple and fast, has a low technical level, is easy to master, and can also achieve the purpose of detection in production, and is suitable for popularization and use. The more commonly used methods are the pH value addition method and the phenol red method. my country's feed standard stipulates that the pH value of urease activity shall not exceed 0.4. Many studies have shown that the urease activity is only in the range of 0.03 to 0.4, and the feeding effect is the best. However, it is best to use the urea-phenol red qualitative method to detect the urease activity in the feed mill site. Therefore, the method is simple and fast, has a low technical level, is easy to master, and can also achieve the purpose of detection in production, and is suitable for popularization and use. 03～0.4, the feeding effect is the best. However, it is best to use the urea-phenol red qualitative method to detect the urease activity in the feed mill site. Therefore, the method is simple and fast, has a low technical level, is easy to master, and can also achieve the purpose of detection in production, and is suitable for popularization and use. 03～0.4, the feeding effect is the best. However, it is best to use the urea-phenol red qualitative method to detect the urease activity in the feed mill site. Therefore, the method is simple and fast, has a low technical level, is easy to master, and can also achieve the purpose of detection in production, and is suitable for popularization and use.

4. The impact of puffing processing on the conventional nutritional components of full-fat soybeans It can be seen from Table 1 that the moisture content of soybeans we use is relatively high. Generally, according to national standards, the moisture content of soybeans should be below 13.5%. Because it is a new soybean, it needs to be processed, and the moisture content of the finished soybean powder is also somewhat high. It can be seen from the data that after dry expansion of raw soybeans, the moisture content is reduced by 34%, and the crude fiber is reduced by 36%. Because at the moment of puffing, the moisture in the feed loses its restraint at high temperature, the crude fiber is hydrolyzed, and the intermolecular connections are broken, resulting in a significant reduction in moisture and crude fiber content. This is also an important reason why raw soybeans can increase the nutritional value after puffing . one. There was a slight increase in protein, mainly due to a decrease in water content, but little change in fat content.

Table 1 Determination of some items of soybean and soybean meal %

Item Raw soybeans Soy flour

Moisture 14.23 9.38

Crude protein 36.65 37.21

Crude fat 17.02 17.11

Crude fiber 6.72 4.35

Loss rate 5.67

5. Treatment after curing. After the soybean meal is marinated, it should be noted that the soybean meal should not be packaged immediately after it comes out, because the temperature of the soybean meal is relatively high at this time, generally 85-95°C. Wrap it immediately, the heat is hard to dissipate, and it takes a long time. The soybean flour in the middle of the high-temperature bag will coke, causing overcooking and protein denaturation, affecting its utilization rate and palatability. Soybean flour should be cooled before packaging after puffing. Special attention should be paid to the high moisture content of the product after wet puffing, which must be fully dried and cooled to achieve safe storage of moisture.