aufkochen

Aufkochen is a German culinary term that describes bringing a liquid or mixture to a full boil. The verb is separable (kochen with the prefix auf), so in use you might hear or see the phrase die Suppe kocht auf. The past participle is aufgekocht. In English it is commonly translated as to bring to a boil or to reboil when referring to heating something to the boiling point.

In cooking, aufkochen is used to heat soups, sauces, milk, and other liquids until they boil. Reaching the boiling point can help dissolve ingredients, activate thickeners such as starches, or ensure uniform temperature throughout the mixture. It may also serve as a step in food preservation or processing, where liquids are heated to boiling as part of safety or preparation procedures. After aufkochen, a cook may reduce heat or switch to a gentler simmer to continue cooking without vigorous boiling.

The term is typically contrasted with köcheln, which means to simmer softly, or with other methods that do not require reaching a full boil. Proper control of the heat is important to prevent scorching of sugary or dairy-based sauces and to avoid over-reduction. In culinary manuals, aufkochen is often described as a preparatory step that enables later stages of a recipe, such as emulsification, reduction, or seasoning.