Changes of nutrients in fish feed during extrusion and expansion production
1. Changes of starch: During the operation of the fish feed puffing machine, starch in the material will undergo gelatinization reaction under high temperature environment, and the gelatinization degree is mainly determined by starch content and moisture content. Under the action of extrusion, the temperature of the material slowly increases, and with the increasing temperature, the permeability of water is also strengthened; The water will be slowly absorbed by the material, the starch in the material will fission, and eventually form a gelatinized state. Under normal circumstances, when starch encounters high temperature in sealed environment, the macromolecular polymer in starch will break off in the room, showing a state of melting, the total content of starch is reduced, and the content of dextrin and reducing sugar is increased.
2. Protein changes: in fish feed, protein is also a very important content, and in the feed formula accounted for a large proportion. The main purpose of protein is to ensure that the fish feed can meet the nutritional needs of the fish, to ensure that the fish can grow. The function of protein is closely related to the stability of fish feed. Its viscosity, elasticity and water absorption all affect the stability of fish feed to some extent. In the process of fish feed expansion, when the temperature reaches 140-200℃ and the pressure is 1.7-6.1MPa, the protein structure changes and develops to the molten state. In this state, the protein will pass through the extrusion plate and die hole, and then suddenly enter the atmospheric environment. Under the influence of hot steam, the porous structure is finally formed.
3. During the operation of the fish feed puffing machine, the lipid substances in the fish feed hydrolyze, and the fat oxidase will gradually lose its own activity, thus improving the stability of the structure of the fish feed. However, due to the high temperature in the extrusion and expansion process, the stability of lipids is destroyed, and hydrolysis, oxidation and polymerization occur. Among them, fish oil, which is rich in unsaturated fatty acids, will break the unsaturated bond in the lipid substance under the polymerization reaction, which reduces the business function of the lipid substance.
4. The change of vitamins, trace elements, in the fish feed in the process of extrusion machine work, there will be a significant change, vitamins and trace elements in the process of expanding, vitamin lose, heat-sensitive vitamins such as Vc, Va are more likely to be destroyed, processing conditions and their chemical structure of vitamin can cause the loss of vitamins, when bulking excessive temperature, pressure and residence time is longer, vitamin loss will be faster, fish feed moisture also can have very significant losses, most of the mineral elements will not have obvious changes, but under the effect of phytic acid oxidation reaction will happen, to some extent reduced the fish feed nutrients.
5. The change of the harmful ingredients in fish feed in fish feed in the process of the extrusion machine work at ordinary times, can not only eliminate the fish feed in various harmful factors such as fatty oxidase, aflatoxin can also for some specific material as raw material to produce fish feed a larger impact, most of the material harmful microbes will be killed in the expansion, enhance the nutritional value of fish feed.
Therefore, the fish feed puffing machine plays a very important role in the production of fish feed. The fish feed produced by the machine has improved the development of the fishery to a certain extent. Jinan FLD Machinery Co., Ltd. Welcome all major customers to consult and order. Contact: Kevin, Tel :86-18660429170. Our company will wholeheartedly provide you with better prices and more reasonable product solutions.
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