Pregelatinized starch
It is a kind of modified starch which is easy to process and widely used. When applied, it just needs to be made into a paste with cold water, eliminating the trouble of heating and pasting. It is widely used in many industries such as medicine, food, cosmetics, feed, oil drilling, metal casting, textile and paper making.
Gluing of starch.
The effect of starch granules dissolving, splitting and forming a uniform paste solution in water at the proper temperature (the temperature required for starch from various sources is different, generally 60~80℃) is called pasting. The essence of pasting is that the hydrogen bonds between the ordered and disordered (crystalline and amorphous) starch molecules in the starch granule are broken and dispersed in water to form a colloidal solution.
The process of pasting action can be divided into three stages.
(1) Reversible water absorption stage, water enters the amorphous part of starch granule, the volume expands slightly, at this time cooling and drying, the granule can recover, and the birefringence phenomenon remains unchanged.
(2) Irreversible water absorption stage, as the temperature rises, water enters the starch microcrystalline interstices, irreversibly absorbing a large amount of water, the birefringence phenomenon gradually blurred or disappeared, also known as crystallization "dissolution", starch granules swell to 50-100 times the original volume.
(3) The starch granules finally disintegrate and all starch molecules enter the solution.