Blanching (or to blanche) is a cooking term that describes a process of food preparation wherein the food substance is rapidly plunged into boiling water and then removed after a brief, timed interval and then plunged into iced water or placed under cold running water. Blanching rapidly heats and then cools the food. This allows the food, usually fruits and vegetables, to firm up and makes the food's natural flavour more pronounced, and is often a preparative technique for freezing food.
Blanching is also an effective method of loosening the skin on fruits or nuts that one may wish to peel, such as tomatoes, plums, peaches, or almonds.
In addition, blanching enhances the color of some (particularly green) ingredients.
Steam blanching is also used to neutralise bacteria and enzymes present in foods so that they may be processed and gain a greater shelf life, such as peanuts.