As a cereal grain, the polished head rice contains about 70% starch.
During the period of its cooking, hot water enters the semi-crystalline
regions of raw starch, breaks down the intermolecular hydrogen
bonds, and binds to the hydroxyl hydrogen and oxygen so that the
chains of starch lose their crystallinity into the amorphous form. This
gelatinized starch is not in thermodynamic equilibrium.