Starch becomes soluble in water when heated. The granules swell and burst, the semicrystalline
structure is lost and the smaller amylose molecules start leaching out of the
granule, forming a network that holds water and increasing the mixture's viscosity. This
process is called starch gelatinization. During cooking, the starch becomes a paste and
increases further in viscosity. During cooling or prolonged storage of the paste, the
semi-crystalline structure partially recovers and the starch paste thickens, expelling
water. This is mainly caused by retrogradation of the amylose