Puffed pet food is a special pet food made by mixing many nutrient raw materials, then puffing or extruding, and then drying, dehydrating, seasoning and other processes. The application of puffing technology in pet food began in the 1950s. The United States first began to use the extrusion principle to produce pet food in order to improve the digestion and utilization rate of feed for dogs. Compared with traditional animal food, the biggest difference of the extrusion puffing process is that it breaks through the inherent general flat die or ring die extrusion process, and as a special pet food manufacturing method, it is designed into the manufacturing process of dog food, making it a pet food that can promote better absorption by pets, more scientific nutrition, and higher palatability. At present, the use of screw extrusion in the production of puffed pet food can be divided into two forms, one is the dry puffing method, and the second is the wet puffing method.
01 Dry puffing
Dry puffing: No water needs to be added to the raw materials during production and processing. The raw materials are not pre-conditioned before entering the puffing bin. All the heat generated during the puffing process is generated by the raw materials through the screw, shear plate and puffing chamber under the action of mechanical extrusion.
02 Wet puffing
Wet puffing: Pre-conditioning is required. The difference between wet puffing and dry puffing is that the raw materials are conditioned in advance before entering the puffing, and the temperature is increased by steam or water for pre-cooking.
Dry puffing uses the heat generated by friction as a heat source for ripening and dehydration of processed products; wet puffing feeds raw materials that are first pre-conditioned, and steam and water and other liquids are injected to preheat and ripen the materials.
For most materials, wet puffing is more efficient than dry puffing, and more energy can be used to increase production, with high production, good product quality, and long service life of wearing parts. Relatively speaking, dry puffing is more suitable for small-volume processing.
03 Conditioning
"Conditioning" means that steam is used to produce heat and moisture on pet food raw materials, so that the starch in the raw materials is pre-gelatinized, the protein is denatured, and the raw material material is softened, which is beneficial to improve the puffing granulation effect and puffing quality of pet food. In the wet puffing process of pet food, pre-conditioning technology is of great significance: improving the ability of puffing granulation, pre-heating the raw materials through pre-conditioning, softening the raw materials, and being more conducive to molding, while reducing the wear of the raw materials on the machinery. Pre-conditioning technology is used to increase the bulk density of the particles, reduce the dust rate, reduce the loss during the processing, and maintain the sanitation of the production environment.
Promote starch gelatinization and protein denaturation, and improve the digestion and absorption of food by pets. According to data, when steam-conditioned, the gelatinization rate of starch can reach 35%~45%, while the gelatinization rate of starch without pre-conditioning is only 15%. More thoroughly kill harmful bacteria. During the pre-conditioning process, high-temperature steam can kill most E. coli and Salmonella, greatly improving the safety and sanitation of pet food. Liquid nutritional raw materials can be easily added to improve the nutritional value of pet food; at the same time, the wet puffing method also has the advantages of good puffing granulation effect and stable puffing rate, but compared with the dry puffing method, it has the disadvantages of expensive equipment, high equipment requirements and complicated operation.
