Why should aquatic feed not be over-extruded?
Over-extrusion of aquatic feed is unscientific
Focusing on apparent shape and overemphasizing the degree of expansion of extruded pellet feed may lead to the production of toxic and harmful substances in feed products, the near-total loss of nutritional components, an increased risk of melamine residues, reduced feed quality and unnecessary production waste. To identify and judge the quality of extruded pellet feed, one should focus on the intrinsic quality indicators of the product and the final aquaculture results, and not mistakenly choose feed products based only on the surface morphology of the pellets
□By Xu Zhongliang, Jiaxing Yusheng Electromechanical Co., Ltd.
The original intention of developing extruded pellet feed for aquatic animals was to make the feed float in water, neither sinking nor scattering, making it easy for fish to ingest and easy to directly observe the feeding state of fish, improving its stability in water, reducing pollution caused by aquaculture, and at the same time pre-digesting nutrients such as starch outside the body and killing pathogenic bacteria in the feed, thereby increasing the feed conversion rate. Experience shows that as long as the degree of expansion of feed pellets is controlled at greater than or equal to 1.4 (the ratio of the particle size of extruded pellets to the diameter of the die holes), the general requirement of not sinking or scattering in water can be met.
Over the past decade, as China has become a major aquaculture country, extruded pellet feed for aquatic animals has developed rapidly, and competition within the industry has become increasingly fierce. Some feed production enterprises do not focus on improving the intrinsic quality of extruded pellet feed for aquatic animals and the final aquaculture results, but instead emphasize apparent shape, requiring the degree of expansion of pellet feed to reach or even exceed 1.8, so that such pellet feed looks like puffy little breads on the surface. However, to achieve such a puffy shape, the temperature and pressure inside the extruder barrel must inevitably be increased. The method is to add friction heat-generating elements and damping devices to the extruder, lock the extruder very tightly, and intensify the mutual shearing and friction between the feed and the friction heat-generating elements and damping devices, as well as between feed and feed, within the extrusion chamber. The instantaneous material temperature generated locally by friction can reach as high as 200°C, which will cause complex changes in the nutritional components of the feed and produce many unfavorable negative factors. Preliminary analysis mainly includes:
1. The substances that make up aquatic feed are mostly organic matter, among which protein accounts for a very high proportion. When the ambient temperature exceeds 195°C, proteins or amino acids undergo a phase change (from solid phase to liquid phase) and decompose instantaneously. Proteins and fats undergo the Maillard reaction (browning reaction) under high temperature and high pressure, and the higher the temperature, the faster the reaction. This reduces the nutritional value of protein. Various heat-sensitive nutritional components are also nearly completely lost. Many organic substances will also decompose under high temperature and high pressure and synthesize new substances, some of which are harmful and toxic.
2. Announcement No. 1218 of the Ministry of Agriculture, issued and implemented on June 8, 2009, "sets the limit value of melamine in feed raw materials and feed products at 2.5 mg/kg; feed raw materials and feed products with more than 2.5 mg/kg shall not be sold."
The industrial production of melamine is usually generated by the decomposition and condensation of urea in an ammonia medium under the catalysis of silicides (380-400°C); it can also be formed by the condensation of dicyandiamide with ammonia, or by the ammoniation and condensation of cyanamide and other substances. Aquatic feed makes extensive use of fishmeal, cakes and meals, and other raw materials with complex compositions, and inevitably contains trace amounts of urea, histamine and silicides. Experience clearly shows that the higher the temperature and pressure during the extrusion process, the greater the tendency for the urea, ammonia or amine salts in the raw materials to produce an increase in melamine, and the increase in melamine produced is positively correlated with the temperature and pressure of the extrusion process. An additional increase in the background melamine residue value inevitably conceals the risk that the feed product may exceed the melamine limit and therefore cannot be sold.
3. After the degree of expansion of the pellets increases, the spacing between feed powder particles becomes larger, and pores on the surface and even inside the pellets increase, causing the bonding performance of the same formula and the same binder to decrease, and therefore the water stability of the pellet feed also decreases accordingly.
4. The friction heat-generating elements of the extruder are increased, and the machine is locked very tightly, which intensifies friction in the extrusion chamber and shortens the service life of various friction elements. In addition, because the machine is locked tightly, the material flow is not smooth, and production capacity will decline noticeably. Energy consumption increases, leading to waste.
Overemphasizing the degree of expansion of extruded pellet feed is beneficial neither from the perspective of feed product safety and nutrition, nor from the perspective of aquaculture production, feed enterprise production management, and economic effects.
The vast number of aquaculture farmers should be made clearly aware that to identify and judge the quality of extruded pellets, one should focus on the intrinsic quality indicators of the product and the final aquaculture results, and not mistakenly choose feed products based only on the surface morphology of the pellets.
We should quickly move out of the mistaken zone of over-extrusion of aquatic feed and change the production process of over-extruded aquatic feed.
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Finally, I systematically understand the disadvantages of over-extrusion. Very well written. Regarding point 3, "decreased bonding performance," I do not quite understand it. Could you elaborate in detail?
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Good post, I learned from it
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Oh, does extrusion still need to reach 190 degrees?? Isn't 110-130 enough??
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This post was last edited by s0311319 on 2009-11-11 16:12
Learned
If extruded excessively, the color of the feed after drying is obviously not very good, wrinkled and puckered
Water stability, I feel it is not very significant, but after absorbing water, the volume change is quite large
It has a certain impact on aquaculture species that require very high stability
As for whether it is scientific or not, it needs actual aquaculture data to speak!
--------------------------------------
Learned.....
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90-105°C low-temperature extrusion; animal-based raw materials should not be extruded.
--------------------------------------
Does extruded feed damage enzyme preparations?? How much damage is there?
[ts]chinson supplemented the following content on 2009-11-18 19:02[/ts]
Does extruded feed damage enzyme preparations?? How much damage is there?
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liuminjia is right. Making aquatic extruded feed does not need to reach 190 degrees. Exceeding 140-160 degrees is abnormal, and the cause should be investigated.
--------------------------------------
Learned, everyone spoke very well/
--------------------------------------
I originally thought the greater the degree of expansion, the better. Thank you!
--------------------------------------
A small reminder: the Maillard reaction does not require the participation of fat, and instantaneous high temperature will not cause serious consequences. This reaction is positively correlated with both temperature and time at the same time!
□By Xu Zhongliang, Jiaxing Yusheng Electromechanical Co., Ltd.
The original intention of developing extruded pellet feed for aquatic animals was to make the feed float in water, neither sinking nor scattering, making it easy for fish to ingest and easy to directly observe the feeding state of fish, improving its stability in water, reducing pollution caused by aquaculture, and at the same time pre-digesting nutrients such as starch outside the body and killing pathogenic bacteria in the feed, thereby increasing the feed conversion rate. Experience shows that as long as the degree of expansion of feed pellets is controlled at greater than or equal to 1.4 (the ratio of the particle size of extruded pellets to the diameter of the die holes), the general requirement of not sinking or scattering in water can be met.
Over the past decade, as China has become a major aquaculture country, extruded pellet feed for aquatic animals has developed rapidly, and competition within the industry has become increasingly fierce. Some feed production enterprises do not focus on improving the intrinsic quality of extruded pellet feed for aquatic animals and the final aquaculture results, but instead emphasize apparent shape, requiring the degree of expansion of pellet feed to reach or even exceed 1.8, so that such pellet feed looks like puffy little breads on the surface. However, to achieve such a puffy shape, the temperature and pressure inside the extruder barrel must inevitably be increased. The method is to add friction heat-generating elements and damping devices to the extruder, lock the extruder very tightly, and intensify the mutual shearing and friction between the feed and the friction heat-generating elements and damping devices, as well as between feed and feed, within the extrusion chamber. The instantaneous material temperature generated locally by friction can reach as high as 200°C, which will cause complex changes in the nutritional components of the feed and produce many unfavorable negative factors. Preliminary analysis mainly includes:
1. The substances that make up aquatic feed are mostly organic matter, among which protein accounts for a very high proportion. When the ambient temperature exceeds 195°C, proteins or amino acids undergo a phase change (from solid phase to liquid phase) and decompose instantaneously. Proteins and fats undergo the Maillard reaction (browning reaction) under high temperature and high pressure, and the higher the temperature, the faster the reaction. This reduces the nutritional value of protein. Various heat-sensitive nutritional components are also nearly completely lost. Many organic substances will also decompose under high temperature and high pressure and synthesize new substances, some of which are harmful and toxic.
2. Announcement No. 1218 of the Ministry of Agriculture, issued and implemented on June 8, 2009, "sets the limit value of melamine in feed raw materials and feed products at 2.5 mg/kg; feed raw materials and feed products with more than 2.5 mg/kg shall not be sold."
The industrial production of melamine is usually generated by the decomposition and condensation of urea in an ammonia medium under the catalysis of silicides (380-400°C); it can also be formed by the condensation of dicyandiamide with ammonia, or by the ammoniation and condensation of cyanamide and other substances. Aquatic feed makes extensive use of fishmeal, cakes and meals, and other raw materials with complex compositions, and inevitably contains trace amounts of urea, histamine and silicides. Experience clearly shows that the higher the temperature and pressure during the extrusion process, the greater the tendency for the urea, ammonia or amine salts in the raw materials to produce an increase in melamine, and the increase in melamine produced is positively correlated with the temperature and pressure of the extrusion process. An additional increase in the background melamine residue value inevitably conceals the risk that the feed product may exceed the melamine limit and therefore cannot be sold.
3. After the degree of expansion of the pellets increases, the spacing between feed powder particles becomes larger, and pores on the surface and even inside the pellets increase, causing the bonding performance of the same formula and the same binder to decrease, and therefore the water stability of the pellet feed also decreases accordingly.
4. The friction heat-generating elements of the extruder are increased, and the machine is locked very tightly, which intensifies friction in the extrusion chamber and shortens the service life of various friction elements. In addition, because the machine is locked tightly, the material flow is not smooth, and production capacity will decline noticeably. Energy consumption increases, leading to waste.
Overemphasizing the degree of expansion of extruded pellet feed is beneficial neither from the perspective of feed product safety and nutrition, nor from the perspective of aquaculture production, feed enterprise production management, and economic effects.
The vast number of aquaculture farmers should be made clearly aware that to identify and judge the quality of extruded pellets, one should focus on the intrinsic quality indicators of the product and the final aquaculture results, and not mistakenly choose feed products based only on the surface morphology of the pellets.
We should quickly move out of the mistaken zone of over-extrusion of aquatic feed and change the production process of over-extruded aquatic feed.
--------------------------------------
Finally, I systematically understand the disadvantages of over-extrusion. Very well written. Regarding point 3, "decreased bonding performance," I do not quite understand it. Could you elaborate in detail?
--------------------------------------
Good post, I learned from it
--------------------------------------
Oh, does extrusion still need to reach 190 degrees?? Isn't 110-130 enough??
--------------------------------------
This post was last edited by s0311319 on 2009-11-11 16:12
Learned
If extruded excessively, the color of the feed after drying is obviously not very good, wrinkled and puckered
Water stability, I feel it is not very significant, but after absorbing water, the volume change is quite large
It has a certain impact on aquaculture species that require very high stability
As for whether it is scientific or not, it needs actual aquaculture data to speak!
--------------------------------------
Learned.....
--------------------------------------
90-105°C low-temperature extrusion; animal-based raw materials should not be extruded.
--------------------------------------
Does extruded feed damage enzyme preparations?? How much damage is there?
[ts]chinson supplemented the following content on 2009-11-18 19:02[/ts]
Does extruded feed damage enzyme preparations?? How much damage is there?
--------------------------------------
liuminjia is right. Making aquatic extruded feed does not need to reach 190 degrees. Exceeding 140-160 degrees is abnormal, and the cause should be investigated.
--------------------------------------
Learned, everyone spoke very well/
--------------------------------------
I originally thought the greater the degree of expansion, the better. Thank you!
--------------------------------------
A small reminder: the Maillard reaction does not require the participation of fat, and instantaneous high temperature will not cause serious consequences. This reaction is positively correlated with both temperature and time at the same time!