Advantages and Disadvantages of Puffing Technology and Its Application in Animal Feed
Puffing technology is a technology commonly used in modern feed processing. After the feed is processed by the expansion technology, the starch can be gelatinized and degraded in the feed, the protein is denatured, the anti-nutritional factor is lowered, and the palatability is increased. However, there are also disadvantages such as the formation of non-digestible substances, destruction of vitamins, and increase of cost. 1 puffing technology Puffing technology means that the material containing certain moisture is sent to the extrusion extruder. Under the push of the screw and the screw, the material moves axially forward, and the mechanical friction between the material and the spiral, the material and the barrel, and the material. The material is strongly squeezed and sheared, and the material is further refined and homogenized, and then the pressure and temperature inside the machine cavity are continuously increased and increased, and the material is under the action of high temperature, high pressure and high shear force. Complex physicochemical changes have occurred in the material components. Finally, the paste material is ejected from the die hole, and a pressure difference is instantaneously generated, and the material is expanded to form a loose, porous, crisp and puffed product. 2 advantages of puffing technology After the feed material is puffed, it has a unique flavor and fluffy feeling, good palatability, high gelatinization degree and good attracting effect. At the same time, the long-chain structure of some organic substances such as proteins and fats becomes a short-chain structure, making it easier for animals to digest and absorb. 2.1 Starch gelatinization and degradation After extrusion and puffing, starch mainly undergoes two changes. First, starch gelatinization, the expansion process dismantles the dense crystal structure of the starch molecules, the crystal structure absorbs the hydrolysate, the hydrogen bond breaks, and the expanded starch particles rupture and become a viscous melt. At the exit of the extruder, due to the sudden drop of pressure, the steam is lost in a large amount, which is the collapse of a large amount of expanded starch granules, starch gelatinization, and the formation of many microporous expanded feed. On the other hand, starch degradation, the average molecular weight of starch is significantly reduced, and oligosaccharides of small molecular structures such as maltodextrin can be produced by cleavage. Gelatinized starch has strong water absorption and a much stronger bonding function than ordinary starch, which can reduce the amount of starch used in production and provide more choices for other raw materials. At the same time, the gelatinized starch can bind the protein tightly to the starch matrix to form a rumen non-degradable protein body, that is, a rumen protein, which improves the utilization of the protein by the ruminant. 2.2 protein denaturation The protein-containing material is subjected to a combination of high temperature, high pressure and high shear force in the extruder. The tertiary and quaternary structure of the protein is destroyed, the molecular structure of the protein is stretched and recombined, the surface tends to be structurally uniform, and the intermolecular hydrogen bonds and disulfide bonds are partially broken, resulting in final denaturation of the protein. The degree of denaturation of the protein is closely related to the parameters during extrusion. Many anti-nutritional factors, such as urease, antitrypsin and hemagglutinin in soybean, mustard enzyme in rapeseed meal and polyphenolic compounds such as mustard meal produced by glucosinolate, are also inactivated in cottonseed. Gossypol and the like. As a high-quality protein feed material, feathers have a protein content of about 75% to 90%, making it a favorite material in feed ingredients. However, the protein of feather meal is mostly a cable-like structure in which several polypeptide chains are arranged along the parallel spiral of the fiber. The chain contains a large number of crosslinks, disulfide bonds and hydrogen bonds to make it have a strong stable structure. The strong hydrophobic force makes it difficult to be digested and used by animals. The untreated feather powder has a very low feeding value and the digestibility is only about 7%. After puffing, the keratin protein in the feather denatures and cleaves the spatial structure of the keratin protein, making it digestible and absorbable, and the digestibility can be increased to more than 70%. 2.3 fat degeneration Extrusion process destroys the cell wall structure of oilseeds and releases the oil therein. This processing method can improve the utilization of oil. Puffing can also form a complex product (lipoprotein) or (lipopolysaccharide) with starch or protein, which reduces the free fatty acid content, and at the same time deactivates the esterase, inhibits the degradation of the oil and reduces the storage and transportation of the product. The rancidity of the oil and fat components is conducive to long-term preservation of the feed. 2.4 increase palatability and digestibility The puffed feed has a small particle size, is crisp, and emits a scorching aroma, which improves palatability. The puffed feed becomes a loose and disordered structure. This change provides a larger contact area for the enzyme, which is beneficial to the contact of the starch chain, the peptide chain and the digestive enzyme, and is beneficial to the digestion and absorption of the feed, thereby improving the digestion of the feed. rate. 2.5 Improve fiber solubility Extrusion can greatly reduce the crude fiber content in the feed. Through the extrusion technology, in the extrusion, due to the high temperature and high pressure until the instantaneous expansion of the outlet, the lignin in the interstitial and cell walls is melted, some hydrogen bonds are broken, and the polymer substance is decomposed into low molecular substances, and the original compact structure It becomes fluffy and releases some digestible material, which improves feed utilization. 2.6 is conducive to feed storage, extend feed shelf life Under the action of high temperature and high pressure and puffing, the material kills the content of mold, bacteria and fungi in the raw materials, thereby improving the hygienic quality of the feed, and effectively reducing the occurrence of diseases such as diarrhea, gastroenteritis and diarrhea. 3 shortcomings of puffing technology During the extrusion process, the Maillard reaction occurs between the reducing sugar and the free amino acid in the feed, which reduces the content of reducing sugar and free amino acid in the feed, resulting in weakening of the effectiveness of the amino acid, and the material is rubbed at high temperature and pressure. As well as the evaporation of water, it will lead to the loss of vitamins, especially the loss rate of water-soluble vitamins is 50%. Therefore, in the process of feeding animals, some extra vitamins should be added to compensate for the loss caused by puffing. 4 application of puffing technology in animal production 4.1 pigs Due to the small stomach volume and the weak digestion and absorption capacity of the intestines, suckling pigs are prone to nutritional diarrhea during the process from eating breast milk to eating feed. Ungelatinized feed, sterilization is not ideal, it is easy to cause the baby's digestive tract stress response, causing diarrhea and diarrhea. The puffed feed will greatly reduce the incidence of diarrhea when feeding weaned piglets, thereby reducing the cost of feeding, shortening the fattening time, and improving economic benefits. 4.2 poultry After the puffing, the feed is granulated, which is beneficial to the feeding of chickens and ducks, improves the wear speed of the feed in the sac, accelerates the digestion and absorption of the feed, and improves the utilization rate of the feed. Since the puffed feed kills a large number of pathogenic bacteria, the disease such as squatting of the bird is reduced. 4.3 ruminant feeding Due to the degradation of fiber in the feed, the soluble fiber increases, which in turn increases the digestion and utilization of the feed by ruminants. Puffing technology can increase the utilization of non-protein nitrogen by ruminants and increase the amount of rumen protein, thus reducing the cost of feeding. 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