Endosperm

The largest portion of a grain kernel containing most of the protein and carbohydrates, but only small quantities of vitamins and minerals. For many types of grain products, such as refined wheat flours, the endosperm is the only part of the grain that is used: the nutritious bran and germ portions of the grain are eliminated. Some grains, such as teff, are so small that it is impossible to extract only the endosperm when milling flour, so the entire grain must be used.