The Extruder For Puffed Snacks

The puffing process of materials in the extrusion and puffing machine can be roughly divided into three stages:

(1) Conveying and mixing stage: After the material enters the extruder from the hopper, it is continuously mixed and raised under the push of the rotating screw.

(2) Extrusion and shearing stage: After the material enters the extrusion and shearing stage, the gap between the screw and the screw sleeve is further reduced, and the material continues to be extruded; when the gap is completely filled, the material is sheared; the strong shear principal stress causes the material agglomerates to break up and produce reflux. The greater the reflux, the greater the pressure. In this stage, the physical and chemical properties of the material change due to the strong shearing effect.

(3) Extrusion and puffing stage: After the temperature of the material rises in the extrusion and shearing stage, it enters the extrusion and puffing stage. As the gap between the screw and the screw sleeve is further reduced, the shear stress also increases sharply, the crystal structure of the material is destroyed, and a textured structure is produced. As the pressure and temperature also increase sharply accordingly, the material becomes a fluid gel state. At this time, the material is discharged from the die hole to normal air pressure, and the water in the material evaporates and expands instantly and cools down, causing the gelatinized starch in the material to expand as well, forming countless fine and porous sponges. After dehydration, the organizational structure of the gelatinized starch changes significantly, the starch is fully gelatinized, has good water solubility, is easy to dissolve, absorb and digest, and the volume of the starch expands several to dozens of times.