Talking about the mechanism of the expansion power
First, the role of high molecular weight materials in the expansion 1 finite run-up of the gel phase in the amorphous zone; puffed food machinery 2 the melting of the crystallites, and the simultaneous hydration and swelling of the molten crystallites and the amorphous gel zone; 3 The hydration of the molten crystallites causes the water in the pellet to redistribute, and the stress generated by the final swelling causes the crystallite deformation to accelerate the melting. 1. The role of starch in puffing The content and distribution of moisture in the starch agglomerate depends to a large extent on the density of the polysaccharide chain and the regularity of the stacking. This is essential for the physicochemical properties and bulking properties of starch. Under hot pressing conditions, changes within the pellet generally involve four different processes: 1 introducing combined water into the microcrystalline region; 1 Excessive water will lead to improper expansion of the adsorbed colloidal area in the material, causing the material to warm up in the pressurizing section, some of the starch has been gelatinized in advance or some of the protein has been prematurely denatured, which hinders the puffing; 2 Even if the material containing excess water undergoes the expansion process, its products will soften due to the high water content of the finished product, and lose the proper flavor of the expanded product. In addition, the material also has a certain moisture content gradient during the expansion process. Different wetness gradients will cause the difference in the generation time of the expansion power and the unevenness of the quality, which will affect the quality of the expansion. 3 Excess water is often free and surface-adsorbed water. They are difficult to replace or occupy the original spatial position of the bound and colloidal moisture molecules. This part of the interstitial water is often not in the closed gas chamber, and it is difficult to become puffed. Power, causing material to puff; 4 When excess water is externally energized, it is easier to preferentially vaporize due to the weak binding force with other components of the material, which occupies effective energy and affects the puffing effect; 1 The conversion of external energy to puffing power must ensure the maximum utilization of energy and the best puffing effect; 2 External energy supply and internal energy changes should maximize the nutritional status of food materials. Therefore, in theory, under the premise of satisfying the above principles, the expansion process conditions can be transformed and combined in different ways, which is new to puffing. The development of process technology and the development of expansion equipment have great guiding significance. Although the puffing power is derived from the power provided by the molecular dispersion of the internal moisture of the puffed material, the power must also be indirectly supplied by external energy. Generally speaking, the external energy supply methods include: heat, mechanical energy, electromagnetic energy, and chemical energy. These energy can be transmitted and converted in a certain form. Acting on water molecules, exacerbating molecular thermal motion and increasing molecular kinetic energy. The design of the external energy transfer must follow: 3 The external energy supply mode must meet the formation mechanism of bulking power; 1. The production of puffing power The result inevitably results in an impact on the structure of the material in contact with it. When the impact force exceeds the force of maintaining the spatial structure of the polymer material and exceeds the supporting force of the material space structure maintained by the polymer material, it will drive the expansion and deformation of the spatial structure of the macromolecular material, and finally cause the quality of the expanded material. Structural changes. The mechanical expansion power of puffed food is mainly caused by the release of energy inside the material.
2. Factors affecting the expansion power
The production of bulking power depends not only on the morphology of the water in the material and its binding properties, but also on the moisture content. In theory, the greater the moisture content of the material, the greater the amount of steam that may be generated. The stronger the expansion power, the greater the effect on the expansion.
3. Transfer of external energy to puffing power
Under the same external energy supply conditions, among the various material components inside the material, due to the small molecular weight, low boiling point and easy vaporization and expansion, the thermal motion of water molecules is first intensified and the molecular kinetic energy is simultaneously increased. Molecular dispersion occurs when the energy obtained by water molecules exceeds the bound extremes of each other. The molecular dispersion of water molecules causes changes in the internal moisture of the material, resulting in phase transitions and vapor expansion.