Fish Feed Extrusion Process Origin
The early-stage extrusion processing was mainly used in the food processing industry. Since the nineteen fifties, America has started to use this technology in the feed processing field, especially for processing pet food and pretreatment of feed ingredients. Till the nineteen eighties, it became the fastest developing technique of the feed processing industry in the world and has started to be applied in each sphere of the feeding stuff industry, widely used for dry pet foods, some applications for livestock feed and fish feed. With the unceasing development of technology and the continuous rise of people’s living standards, the growth of aquaculture must follow the principle of producing green food without pollution, bringing significant attention and lots of intensive study on aqua feed production technology
. There is a consensus that adopting an extrusion process to make fish feed
is the major means to ensure the production of high-quality and safe aquatic products for human health, which is also a trend for the feed industry to progress in the future.
What is the Fish Feed Extrusion Process
The commercial fish feed extrusion process refers to cooking the mixture of feed ingredients under high temperature, moisture, and high pressure by means of a fish feed extruder within a short time, whereby the high temperature is a direct result of friction(dry extrusion) or preconditioning and steam injection (wet extrusion). As a technological treatment, extrusion can make it possible to process a variety of fish feed ingredients, such as soybean, corn, rice, peas, and raw materials with high water content. According to the moisture content of raw materials treatment, the fish feed extrusion process can be divided into two types – dry type extrusion and wet type extrusion.
- Dry-type extrusion process: in the process of extruding, it adopts the heat from friction for warming materials, forces materials to pass through a die hole, and gets certain pressure simultaneously under the action of screw extrusion. After extruding out of the die hole, material pressure will decrease sharply and moisture will evaporate so as to achieve the goal of extrusion. During this whole process, water content is always about 15% – 20%.
- Wet-type extrusion process: Its principle is similar to that of dry-type extrusion, but it needs to add water and vapor to make moisture up to 20% or even over 30% because the rising of materials temperature depends on the addition of vapor.
Currently, the main extrusion equipment applied in aquatic feed production is a single screw fish feed extruder which is also divided into dry type fish feed extruder and wet type fish feed extruder machine. With different parameters and feed formulation, fish farmers and feed plants can make floating, sinking, and slow-sinking feed with high quality and nutrition so as to adapt to the diverse ingestion requirements of various aquatic animals. Adopting alloy steel as material, Our dry-type fish feed extruder has been widely used in small-scale and medium-scale fish farms or feed plants to produce aqua feed and also dog/cat pet feed in virtue of its simple structure and low noise. Other than the dry type, the wet type fish feed extruder machine is equipped with a boiler that can add vapor constantly into the chamber when extruding feed ingredients, which makes it widely applied to produce floating fish feed pellets for fish farms, aquaculture, and even poultry farms.
Tips when operating fish feed extruder:
- Pay more attention to safety. Stay away from the feed inlet when the machine runs. For adding raw materials, operators should use a stick rather than use hand.
- The raw materials should be added before the machine runs.
- When blocking, please turn down the extruder instantly.
- Remember to check the degree of tightness elasticity of the belt, avoiding capacity decrease caused by the belt slipping.
- Regularly change the lubricating oil for the machine.
The basic function of fish feed produced through the extrusion process is to kill the germ, mycete, and fungus in feed ingredients, improve the hygienic quality, and provide safe fodder for fish and other aquatic animals. Besides, there are some other obvious advantages of extruded aqua feed:
- High digestive utilization ratio: In the process of extruding, the heat, steam, pressure, and other mechanical actions can promote the degree of starch pasting, break and soften the cell wall part of fiber structure, and release some digestible materials, which is in favor of the digestion and absorption for aquatic livestock.
- Slight pollution to the environment: with good stability in water, extruded fish feed makes it possible to decrease the dissolution and sediment of feed nutrition and then reduce loss and waste, alleviating water pollution.
- Convenient feeding management: Extruded fish feed can float on water for a long time, which makes it easier to observe fish ingestion so as to adjust feeding quantity timely and master fish growth and health state.
In addition, with a longer and easier storage period, fish feed via the extrusion process, including floating, sinking, and slow sinking types, also can satisfy different demands of aquatic animals with various ingestion habits. All in all, extruded fish feed has gained great popularity among fish farms and other aquaculture industries around the world.