Fine flour differs from normal wheat flour by being thoroughly sifted, and a soft wheat, high in starch, is used. This flour is best for cakes, biscuits and baking. Refined wheat flours are, by law, enriched with thiamin, riboflavin, niacin and iron, and fortified with folic acid.
Flour from "hard" wheat - best for bread making- is higher in protein—including gluten, which makes dough sticky, elastic and able to hold air bubbles formed by a leavening agent as the dough rises. Flours from "soft" wheat have less protein and less elastic quality, so they are better for delicate pastries and cakes.