The gelatinization temperature of starch depends upon plant type and the amount of water present, pH, types and concentration of salt, sugar, fat and protein in the recipe, as well as starch derivatisation technology are used. Penetration of water thus increases the randomness in the starch granule structure, and causes swelling eventually amylose molecules leach into the surrounding water and the granule structure disintegrates.Under the microscope in polarized light starch loses its birefringence and its extinction cross. Heat causes such regions to become diffuse, the amylose chains begin to dissolve, to separate into an amorphous form and the number and size of crystalline regions decreases. At ambient temperatures these crystalline regions do not allow water to enter. Water then enters via amorphous regions into the tightly bound areas of double helical structures of amylopectin.During heating, water is first absorbed in the amorphous space of starch, which leads to a swelling phenomenon.Three main processes happen to the starch granule: granule swelling, crystallite or double helical melting, and amylose leaching. This irreversibly dissolves the starch granule in water. Starch gelatinization is a process of breaking down the intermolecular bonds of starch molecules in the presence of water and heat, allowing the hydrogen bonding sites (the hydroxyl hydrogen and oxygen) to engage more water. Not to be confused with Gelatin, which consists of protein instead of starch.
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