To gelatinise is to make something gelatinous — to convert a liquid, batter, or mixture into a jelly-like state — or, of a substance itself, to become gelatinous. In the kitchen it describes what happens when gelatin, agar, or pectin is dissolved in a hot preparation that then sets on cooling: stocks turn to aspic, fruit juices to jellies, creams to bavarois. In cereal science the same verb covers starch gelatinisation, the irreversible swelling and bursting of starch granules in hot water that thickens sauces, sets bread crumb, and makes rice and pasta digestible. Both senses describe a fundamental texture transformation in cooking: from fluid to structured, from pourable to sliceable, driven by heat, cooling, and the chemistry of gelling molecules.