First is dry puffing method and the second is wet puffing method.
Dry puffing needs to add moisture to the raw materials in the production and processing. The raw materials are not pre-conditioned before entering the puffing bin. and generated in the puffing cavity.
The difference between the wet puffing method and the dry puffing method is that the raw materials are prepared in advance before entering the puffing, and the temperature is increased by steam or water and pre-cured. The so-called conditioning means that the raw material of pet food is heated and humidified by steam, so that the starch in the raw material is pre-gelatinized, the protein is denatured, and the raw material is softened.
In the wet puffing process of dog food, the preconditioning technology is very important:
1. Improve the ability of puffing and granulating. By pre-conditioning and tempering, the raw materials are subjected to a wet-heat reaction with steam in advance, and the raw materials are softened, which is more conducive to forming, and at the same time reduces the wear and tear of the raw materials on the machinery;
2. Improve the bulk density of particles, reduce the dust rate, reduce the loss in the process of dog food processing and maintain the hygiene of the production environment through pre-modulation technology;
3. Promote starch gelatinization and protein denaturation, and improve the digestion and absorption of food by pets. According to data, the gelatinization rate of starch can reach 35%~45% after steam conditioning. The starch gelatinization rate is only 15%;
4. Kill harmful bacteria more thoroughly. High temperature steam can kill most of Escherichia coli and Salmonella in the preconditioning process, which greatly improves the safety and hygiene standards of pet food and dog food;
5. Through conditioning technology, it is convenient to add liquid nutritional raw materials, which improves and increases the nutrition of pet food.
At the same time, the wet puffing method also has the advantages of good puffing granulation effect and stable puffing rate. In the process of dog food processing, the wet puffing method and pre-conditioning technology have a very important role and significance. However, compared with the dry puffing method, it has the disadvantages of expensive equipment, high equipment requirements, and complicated equipment control.
According to the method of quenching and tempering, there are two kinds of dry puffing method and wet puffing method mentioned above. According to the screw structure of the puffing equipment, it can be divided into single-screw extrusion puffing method and twin-screw extrusion puffing method. kind.
The puffing process of the single-screw extrusion puffing method is relatively simple and has a wide range of applications. It can be used for products with high water content and fat content as high as 17% or more.
Compared with the single-screw extrusion method, the twin-screw extrusion method has relatively complex equipment and structure, but it has many advantages such as stable extrusion performance, high product yield, high production efficiency, and basically sterile products after extrusion.
In the processing technology of pet food and dog food, the extrusion process has been widely used in recent years. Especially since the 1980s, it has developed rapidly in pet dry food, semi-dry food, and pet snack food. The technology has greatly improved the palatability, nutrition, digestion and absorption, hygiene and safety, transportation, storage and other aspects of pet food, which has a pivotal and positive significance.
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