Blanching (cooking)

Blanching is a cooking process wherein the food substance, usually a vegetable or fruit, is plunged into boiling water, removed after a brief, timed interval, and finally plunged into iced water or placed under cold running water (shocking or refreshing) to halt the cooking process.

The meaning of blanch is "to whiten", but this is not always the purpose of blanching in cooking. Food is blanched to soften it, or to partly or fully cook it, or to remove a strong taste (for example of cabbage or onions).

When almonds or pistachios are blanched, the skin of the nut (botanically the seed coat surrounding the embryo) softens and can be easily removed later.

Other definitions

Blanching may simply mean boiling in water for an extended period to remove unpleasant flavours such as tannins. For example, a recommended treatment for African yam bean (Sphenostylis stenocarpa), is dehulling followed by blanching in water for 40 minutes at 100 °C.

It is recommended that protein-rich salads to be eaten cold (e.g., tuna, turkey, ham, shrimp, lobster, and chicken) be prepared by immersing these protein foods in boiling water for 30 seconds followed by fast chilling. In addition celery, "which is almost always a component of these salads ... should be treated so as to minimize its bacterial content".