Excessive expansion of aquatic feed is unscientific

Paying more attention to the apparent shape and overemphasizing the expansion degree of expanded pellets may lead to the production of toxic and harmful substances in feed products, the loss of nutrients, increase the risk of melamine residue, reduce feed quality and unnecessary production waste. In order to identify and judge the advantages and disadvantages of expanded pellets, we should pay attention to the inherent quality index of the products and the final breeding effect. We should not mistakenly select the feed commodity □ Wen / Jiaxing Yusheng Mechanical and Electrical Co., Ltd. Xu Zhongliang on the basis of the surface shape of the pellets. The original intention of people in developing aquatic expanded pellet feed is to make the feed float in the water, not sink or disperse, facilitate the intake of fish, and facilitate the direct observation of the feeding state of fish. Improve its stability in water, reduce water pollution caused by culture, and predigest nutrients such as starch in vitro to kill pathogenic bacteria in feed, so as to improve feed conversion rate. Experience shows that as long as the expansion degree of feed particles is greater than or equal to 1.4 (the ratio of expanded particle size to discharge mold hole diameter), the general requirement of not sinking in water can be achieved. In the past ten years, as China has stepped into a large aquaculture country, aquatic expanded pellet feed has developed rapidly, and the competition among industries has become increasingly fierce. some feed production enterprises do not pay attention to improving the inherent quality of aquatic expanded pellet feed and the final effect of breeding, but pay more attention to the apparent shape, requiring the expansion degree of pellet feed to reach or even exceed 1.8, so the surface of pellet feed looks like puffy buns. Do not realize that in order to achieve such a loose shape, the potential must increase the temperature and pressure in the cavity of the extruder. The method is to add friction heating element and damping device in the extruder to lock the extruder tightly and aggravate the mutual shearing and friction between feed and friction heating element and damping device, feed and feed in the puffing cavity. The instantaneous feed temperature produced by friction is as high as 200℃, which will cause complex changes in the nutritional composition of the feed and produce a lot of adverse negative factors. The preliminary analysis is mainly as follows: 1. Most of the substances that make up aquatic feed are organic matter, of which protein accounts for a high proportion. When the ambient temperature exceeds 195 ℃, the protein or amino acid will undergo phase transition (from solid phase to liquid phase) and decompose instantly. Maillard reaction (blackening reaction) occurs between protein and fat under high temperature and high pressure, and the higher the temperature, the faster the reaction. The nutritional value of protein was reduced. All kinds of heat-sensitive nutrients have also been lost. There are many organic substances that will decompose under high temperature and high pressure and synthesize new substances, some of which are harmful and toxic. 2. Ministry of Agriculture notice No. 1218, issued and implemented on June 8, 2009, "set the limit of melamine in feed raw materials and feed products at 2.5 tons per kilogram, and feed raw materials and feed products higher than 2.5 tons per kilogram shall not be sold." The industrial production of melamine is usually formed by the decomposition and condensation of urea in the medium of ammonia and under the catalysis of silicide (380400 ℃), or by the condensation of dicyandiamide with ammonia or by ammoniation condensation of amino cyanide. Aquatic feed uses a large number of fish meal, cake and other complex raw materials, which inevitably contain trace amounts of urea, histamine and silicide. Experience shows that the higher the temperature and pressure of urea, ammonia or amine salt in raw materials, the higher the increase of melamine, and the increment of melamine is positively correlated with the temperature and pressure of the extrusion process. The additional increase in the background residual value of melamine is bound to lurk the risk that the limit of feed product melamine exceeds the limit and cannot be sold. 3. With the increase of the expansion degree of the particles, the distance between the feed particles is enlarged, and the surface and even internal pores of the particles are increased, which results in the decrease of the bonding properties of the same formula and binder, so that the stability of the pellet feed in water also decreases. 4. The friction heating element of the extruder increases, and the machine is locked tightly, which aggravates the friction in the puffing cavity and shortens the service life of all kinds of friction elements. In addition, due to the poor material flow after the machine is locked, the production capacity will be significantly reduced. Increased energy consumption leads to waste. Excessive emphasis on the expansion degree of expanded pellet feed is not beneficial no matter from the point of view of the safety and nutrition of feed products, or from the management and economic effect of aquaculture production and feed enterprise production. The majority of farmers should be made clear that the advantages and disadvantages of extruded pellets should be identified and judged, and attention should be paid to the inherent quality indicators of the products and the final culture effect, and feed commodities should not be mistakenly selected only on the basis of the surface shape of the particles. We should get rid of the misunderstanding of excessive expansion of aquatic feed as soon as possible and change the production process of excessive expansion of aquatic feed. Finally, I systematically learned the disadvantage of over-expansion and wrote it very well. For the third point in the "bond performance decline" is not very clear, can you elaborate? -- easy to paste, learn-- Oh, does the puffing still reach 190 degrees? Isn't it just 110: 130? -- at last, this post was edited by s0311319 at 16:12 on 2009-11-11. If the puffing is excessive, the color of the material is obviously not very good after drying. Zou Baba's water stability. I don't think it's very big, but the volume changes to a lot after water absorption. Yes, it needs to be very stable. Sexual breeding varieties have a certain impact as for the science is not scientific needs the actual breeding data to speak! -- studying. -90-105 °C low temperature expansion; animal raw materials should not be expanded. Is the expanded feed harmful to the enzyme preparation? How much damage is there? [ts] chinson added the following at 19:02 on 2009-11-18 19:02 [/ ts] is extruded feed harmful to enzyme preparations? How much damage is there? -- liuminjia is right. For aquatic puffing materials, it is not necessary to reach 190C. If it exceeds 140C-160C, it is not normal. We need to find out the cause.-- to learn. Everyone said very well /-I only thought that the bigger the expansion, the better. Thank you! A little hint, Maillard does not need the participation of fat, and the instantaneous high temperature will not cause serious consequences, this reaction is positively related to temperature and time at the same time!