Fish Feed Machine Knowleagde

Proper processing of starch-based raw materials can improve the digestibility of pet food. The degree of difficulty of processing varies with the variety and source of starch or starchy grains. Corn and tubers are easy to expand. When used as the main source of starch, the bulk density of pet food products is generally low. In contrast, wheat and rice or flour require more power to obtain similar bulk density and yield. Even within the same grain variety, there are still differences in its processability. Soft wheat and its by-products are easier to puff than durum wheat, which contains more protein.

Protein material
Unripe rapeseed protein is one of the main components of most pet foods and is partially soluble in water. This kind of protein will become malleable after being subjected to the conditions of temperature, moisture and residence time in the extrusion system, forming a good coating layer outside its cell structure, and at the same time losing water solubility due to denaturation. Once the protein loses its water solubility, it loses many functional properties and even becomes inactive, that is, it is difficult to reproduce its ductility. Therefore, many available animal protein raw materials have little effect on product expansion due to their low protein solubility, and may even hinder product expansion.
Many plant proteins have high water solubility, and this protein can be processed into a structured protein product through extrusion and maturation. The bulk density of the product is controlled by the extrusion process, which is very similar to the bulk density of starch materials. Because feed materials have different processability, mixing starch-based raw materials with protein-based raw materials can produce products of different quality.

During the extrusion and expansion period, if the starch content of the product is high, it is most conducive to the expansion of the product, followed by vegetable protein, and animal protein has no effect on the expansion, and even hinders it. Therefore, in those formulas that limit the amount of starch due to the high protein content, the starch raw materials must be pure starch or strictly selected grains, and only in this way can the best puffing be ensured. If the starch content cannot reach the level required for proper puffing, plant proteins such as wheat gluten or soybean meal should be added to promote puffing.

Fat or lipid material
Fat or lipids not only enhance the chewiness and toughness of feed similar to protein, but also have lubricity and elasticity. When the total fat content is less than 8%, the puffing performance of pet food can be enhanced, but when the fat content is higher than 8%, the dough strength and puffing performance will be weakened, and the texture of the product will become soft. When producing high-energy pet food with a processed fat content of more than 17%, it is recommended to spray the fat into the product from the outside after the product is dried and cooled.
The source of fat also has an impact on the puffing rate. The fat provided in the form of a specific raw material has less impact on puffing than the fat added in the form of pure fat or almost pure fat. For example, the effect of providing fat with full-fat rapeseed on puffing It is smaller than pure rapeseed oil.
Adding 0.5% to 1% monoglyceride in pet food formulations can eliminate rough surfaces, reduce fine dust, and give the product a more obvious shape. In addition, monoglycerides can form complexes with amylose and protein, thereby reducing the viscosity of many puffed products.

Crude fiber raw materials
The cellulose and hemicellulose in the crude fiber are relatively inactive ingredients in the feed. When their content accounts for more than 15% of the total weight of the mixture, the expansion performance of the product will be weakened.

Ash raw materials
Low ash raw materials can improve the expansion performance of the product and reduce the metal wear of the extruded parts. From the perspective of nutrition and health, the choice of lowash raw materials is particularly important for the production of cat food.
Most pet food formulations contain cellulose, minerals, salt, vitamins and color enhancers, emulsifiers, etc. The increase in the content of these ingredients or raw materials will reduce the expansion performance of the product.