The equipment for processing extruded feed has also made great progress in China in recent years, and the market share of domestic equipment has been increasing.

Processing principle and process:

1. Conditioning: The material passes through the conditioner, where it is humidified, heated, and stirred by the conditioner blades for conditioning.

2. Extrusion: The feed raw materials pass through the feeding section, soft extrusion section, and melt homogenization section of the 6# extrusion screw in the extruder to form a high-temperature, high-pressure, high-shear, and high-moisture molten material.

3. Expansion: When the feed in a high-temperature and high-pressure state is extruded through the 8# extrusion die hole, it suddenly encounters a normal temperature and pressure environment, and the internal moisture evaporates instantly, producing a strong steam explosion, causing the feed volume to expand rapidly, forming a porous and loose particle structure.

Advantages of extruded feed:

1. The extruded feed is in granular form, with a large surface area and porous structure, which is easy for animals to eat and digest.

2. The processing parameters can be adjusted as needed to produce floating or sinking feed to adapt to the feeding habits of different aquatic animals.

3. High temperature treatment causes starch to gelatinize and convert it into easily digestible dextrin and oligosaccharides, thereby improving the digestibility of starch.

4. The protein molecular structure is moderately denatured at high temperature, exposing more peptide chains, which is conducive to enzyme hydrolysis and improves the bioavailability of protein.

5. High temperature and high pressure can destroy anti-nutritional factors in feed (such as antitrypsin, phytic acid, etc.), reducing their hindering effect on the absorption of nutrients.

6. High temperature treatment effectively kills pathogenic microorganisms and parasites, and at the same time helps to remove some mycotoxins and improve the safety of feed.

7. Extruded feed has strong bonding stability, which can reduce the dissolution and precipitation loss of feed nutrients in water. It can also avoid feed residues in water and reduce water pollution.

8. Reduce the occurrence of diseases. Feed raw materials often contain harmful microorganisms, and the high temperature, high humidity and high pressure of puffing can kill most of the harmful microorganisms.

Disadvantages of extruded feed:

1. Increased processing cost: Compared with ordinary pellet feed, the production process of extruded feed is more complicated, and the equipment investment and energy consumption are higher, resulting in higher costs.

2. Storage and transportation: Due to its porous structure, it may be more hygroscopic, and has higher requirements for storage conditions and packaging. It is necessary to pay attention to moisture-proof during long-distance transportation.

3. Loss of nutrients: Vitamins, enzyme preparations, amino acids and microbial preparations are usually sensitive to temperature. For products produced by high temperature and high pressure processes, their loss rate is relatively large. It can be considered to use post-spraying process to improve.