The core of the working principle of extrusion equipment is to use sudden pressure changes to achieve material expansion. The entire process can be briefly summarized into the following two key stages:
1. Pressurized heating gelatinization After the material (such as rice, corn flour) is fed into the extruder, it is pushed forward by the screw. During this process, the material is subjected to strong extrusion, friction and shear action, resulting in a sharp increase in its internal pressure and temperature (pressure up to 3-10 megapascals and temperature up to 120-170 degrees Celsius). In this high-temperature and high-pressure environment, the starch in the material will gelatinize, and the protein will also denature, eventually turning into a molten paste.
2. Instantaneous pressure relief and expansion When the gelatinized high-temperature and high-pressure material is extruded from the die hole at the end of the extruder, it will instantly enter the atmospheric pressure environment. Due to the sudden drop in external pressure, the superheated moisture inside the material quickly vaporizes and evaporates, producing an effect similar to an "explosion", causing the volume of the material to expand rapidly many times, thus forming a loose and crispy structure full of micropores inside.
To put it simply, it is to make the food fluffy and porous by "pressurizing and heating first, and then releasing instantly".
English
中文简体