Refined green products, such as flours and cornstarch, are used as

Thickeners

Explanation:

Cereal or Grain products, such as rice, wheat, maize(corn) , barley are subjected to milling and refining to give us byproducts such as cornstarch and flour.

During the milling and refining process, the outer covering of the grains which is usually contains a lot of fiber is lost, sometimes the germ and the proteinous part to can also be lost during this process and this is dependent on the byproduct you want to obtain.

Cornstarch has a very high thickening ability than flour because it gelatinizes more easily than flour. But both Corn starch and Flour are very good thickening agents.

Flours and cornstarch are used as thickeners in soup and sauces such a gravy, roux for macaroni and cheese e.t.c