1 Puffing snacks technology
Puffing technology refers to the material containing a certain amount of moisture is sent to the extruder. Under the push of the screw rod and the screw, the material moves forward in the axial direction. The material and the screw, the material and the barrel, and the mechanical friction inside the material The material is strongly squeezed, stirred, and sheared to further refine and homogenize the material. With the increase of the pressure and temperature inside the cavity, the material is subjected to high temperature, high pressure, and high shear forces. Make the physical and chemical changes of the material components complicated. Finally, the pasty material was sprayed from the die hole, a pressure difference was instantaneously generated, and the material was puffed, thereby forming a loose, porous, crispy puffed product.
2 Advantages of puffing technology
After the feed ingredients are puffed, they have a unique flavor and fluffy feel, good palatability, high degree of gelatinization, and good food attraction. At the same time, the long-chain structure of some organic substances such as proteins and fats has become a short-chain structure, making it easier for animals to digest and absorb.
2.1 Starch gelatinization and degradation
After extrusion, starch has two main changes. The first is the gelatinization of starch. The dense crystal structure of starch molecules is disintegrated during the puffing process. The crystal structure absorbs hydrolysate and hydrogen bonds are broken. At the exit of the extruder, due to the sudden pressure drop, a large amount of steam was lost instantly. A large number of extruded starch particles disintegrated and the starch gelatinized, forming many microporous extruded feed. On the other hand, starch degradation, the average molecular weight of starch is significantly reduced, and small molecules such as maltodextrin can be produced by cleavage. Gelatinized starch has a strong water absorption and a much stronger adhesion 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 tightly bind the protein with the starch matrix to form a rumen-indegradable protein body, that is, a rumen-passing protein, which improves the use of protein by ruminants.