Starch gelatinization

Starch gelatinization is the swelling and structural change of starch granules as they absorb water and are heated. It releases starch molecules into the surrounding liquid and thickens many mixtures.

Starch granule: A microscopic, semi-crystalline particle in which plants store starch. Gelatinization begins as water enters these organized particles.
Starch: A plant storage carbohydrate made of glucose polymers, chiefly amylose and amylopectin. Gelatinization is the heat-and-water transformation of this carbohydrate.
Roux: A cooked mixture of flour and fat used to thicken sauces and soups. Its thickening depends on starch gelatinizing after liquid is added.
Dextrinization: The breakdown of starch into shorter chains, commonly caused by dry heating or acid treatment. Unlike gelatinization, it involves cleavage of starch chains rather than mainly water-driven granule disruption.
Amylose: A mostly linear glucose polymer and one of the two main components of starch. Heating can release amylose from granules into the surrounding water.
Hydrogen bond: An attraction between a hydrogen atom bonded to an electronegative atom and another electronegative atom. Water disrupts interactions that help stabilize starch's ordered regions.
Cornstarch: A starch extracted from maize kernels and commonly used as a food thickener. Heating its aqueous suspensions produces the familiar thickening associated with gelatinization.
Melting: A phase transition in which a solid becomes a liquid as temperature rises. Gelatinization is a complex change in hydrated granules, not simply melting.
Amylopectin: A highly branched glucose polymer and the other main component of starch. Its branching and crystalline organization help determine how granules swell.
Water activity: A measure of water's availability for chemical reactions and microbial growth in a material. Available water affects whether starch granules can swell during heating.

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