Blanching is a cooking technique involving boiling food (usually vegetables and fruits) in water for a very short time. Blanching is often followed by plunging the food into ice water to stop the cooking process. Though the word means to make something white or pale, blanching certain vegetables like broccoli will make their colors more vivid.
Vegetables are often blanched prior to freezing or canning. This helps preserve the food by slowing down or halting enzyme action that causes foods to break down, losing color, flavor, and nutritional value.
Blanching is similar to parboiling, which also involves boiling food briefly in water. Certain vegetables may benefit from being blanched or parboiled before being stir-fried. One quick way to blanch vegetables is to boil fresh vegetables in water, with salt, for about 30 seconds to 1 minute, before immediately draining and freezing them.