1. Extruded fish food Processing machine is done by combining the effects of water, pressure, temperature and mechanical shear. During extrusion curing, the temperature in the machine boring can reach 90 ~ 200%, and the duration of extrusion is in the range of 2 ~ 30 seconds. The extruded product undergoes a series of physical and chemical changes, such as starch gelatinization, protein denaturation, enzymes, toxic components and inactivation of microorganisms. Processing puffed fish feed requires injecting steam and water, and its materials should contain at least 20% starch, which mainly plays the role of binder and energy substance. The temperature of the extruded product should be 125 to 138 before exiting the ring die, 34 to 37 atmospheres (33 to 36 kg / cm2), 25 to 27% moisture; after extrusion, the bulk density should be 320 to 400 g / L, and the moisture 21 ~ 24. When the extrudate loses 3 to 4 percentage points of water when it is ejected from the mold, the pressure is suddenly released at the moment when the extrudate is ejected from the mold, so that the superheated water becomes steam and the moisture of the extrudate is reduced. Many small bubbles are generated to reduce the density. Squeeze the feed to float. Drying the fish feed further (usually below 10% moisture) can also improve floatability. The bulk density of 480g / L is considered to be the turning point of the pellet feed floatation. If the bulk density is lower than that, it will float, and if it is higher than this bulk density, it will sink.
2. Types and Structures of fish food Processing machine
There are many types of extruders on the market. Basically, they can be divided into single-screw extruders and twin-screw extruders. Single screw extruder can be divided into wet curing extruder, dry curing extruder and cold forming extruder. The extruder generally consists of four parts, including the feeding system, the modulator, the boring and cutting device of the extruder. The variable-speed feeding screw in the feeding system feeds the raw materials into the pre-conditioner. The operator can monitor and monitor the feeding situation through the high and low level indicators and visual glass windows. The modulator is filled with water and heat in the form of steam. The whole modulation process lasts 5 minutes and can complete 40-50% curing. Extruder boring includes a head and a screw. The function of the screw is to advance the material and control the curing process in the extruder. The screw in the feed section advances the material, usually the screw is deeper; the middle section screw stirs and kneads the material; the final section screw gradually tapers, so that the material is molded out into the final product.