How does blanching work chemically?

Blanching is a cooking process in which food is immersed in boiling water for a short period to partially cook it. The purpose of blanching is to inactivate enzymes that cause vegetables to lose their color, flavor, and nutrients, and to remove undesirable substances such as dirt and bacteria.

The chemical changes that occur during blanching are primarily due to the heat from the boiling water. When vegetables are placed in boiling water, the heat causes the cell walls to break down and the enzymes to become denatured. Denatured enzymes are no longer able to function, so they cannot cause the vegetables to lose their color, flavor, or nutrients.

Blanching also removes undesirable substances such as dirt and bacteria from vegetables. The heat from the boiling water kills bacteria and other microorganisms, and the water helps to dissolve dirt and other particles.

The amount of time that vegetables should be blanched depends on the type of vegetable. Leafy greens such as spinach and kale should be blanched for only 30 seconds to 1 minute, while root vegetables such as potatoes and carrots should be blanched for 2 to 3 minutes.

After blanching, vegetables should be immediately cooled in cold water to stop the cooking process. This helps to preserve the vegetables' color, flavor, and nutrients.