Gelatin

Gelatin is a colorless, flavorless protein derived from collagen, sold as granules or flexible sheets. It blooms in cold liquid and melts when heated, setting to a clear, springy gel as it cools. Cooks use it to stabilize mousses, panna cotta, bavarois, and savory aspics, and to clarify stocks.

Traditional kitchens extracted it by simmering bones and skins; modern production hydrolyzes pork or beef collagen at industrial scale. It became standard in European pastry and charcuterie and is now common worldwide, with fish-based versions used where dietary laws restrict pork or beef.