blanching

Blanching is a cooking technique in which foods, typically vegetables or fruits, are briefly immersed in boiling water or exposed to steam to halt enzyme activity, brighten color, improve texture, and reduce surface microbes. It is often followed by an immediate ice bath to stop cooking.

Two common methods are hot water blanching and steam blanching. In hot water blanching, the food is submerged in rapidly boiling water for a short, product-specific time, then transferred to ice water to stop the cooking process. Steam blanching uses steam above boiling water for a shorter or similar duration.

Times vary by item. Examples: beans 2-3 minutes, broccoli 2-4, carrots 3-5, peas 2-3, and tomatoes about 30-60 seconds to loosen skins. After blanching, foods are usually cooled quickly and drained.

Purposes include preserving color and nutrients, softening skins for peeling (as with tomatoes, almonds, peaches), reducing microbial load, and preparing produce for freezing or canning. Blanching can also reduce bitter flavors in some greens and make vegetables more uniform for drying or processing.

Nutritional impact is mixed: blanching can cause some water-soluble nutrients to leach into blanching water, but losses are minimized by short times and rapid cooling; steaming tends to retain more nutrients than boiling.

Etymology from French blanchir, meaning to whiten. In practice, blanching is a preparatory step in canning, freezing, peeling, and cooking, distinct from parboiling or full cooking.