Why must grains be cooked in liquid?

Grains must be cooked in liquid because they contain starch, a complex carbohydrate that needs to be hydrated in order to be digestible. When grains are cooked in liquid, the water molecules penetrate the starch granules and cause them to swell and burst, releasing the starch molecules into the water. This process is called gelatinization, and it is what gives cooked grains their characteristic soft and chewy texture.

Grains must not be cooked in boiling water, as this can cause them to break down and become mushy. Instead, they should be cooked in simmering water or broth, which allows the starch to gelatinize slowly and evenly. The recommended ratio of water to grains is 2:1, but this can vary depending on the type of grain being cooked.