It may be milled in a similar process to wheat. Its germ is rich in oil, which is refined to produce corn oil. Barley is mainly sold as pearl barley, which is the whole grain with its husk removed Brown rice has its outer husk removed, and white rice is milled and polished further to remove the bran and germ. There are many different types of rice, categorised by size, shape and the region where they are grown. Rice can be ground to make flour.
Rye contains little gluten, so produces breads with low volume and a dense texture.
Oats are rolled rather than crushed during processing. Coarse, medium and fine grades of oatmeal are available. The amount of protein in each cereal differs, and this affects the final product. Bread, with its characteristic open texture and appearance, relies on high protein flour, eg wheat flour. In products such as cakes, biscuits and pastry, low protein cereals are used to produce crumbly and light textures.