The endosperm is the potential white flour within the centre of the wheat grain. When milled, the endosperm fractures along the cell walls, and separates from the bran layers.
The ease of separating the endosperm from the bran layers is determined by the wheat's characteristics. Hard wheats (used for breadmaking) will allow easy separation, whilst the endosperm of soft wheats (used for biscuit flours) does not separate as cleanly from the bran layers.
The bran layers of the wheat grain consist of four separate layers: the pericarp; testa; nucellar layers and aleurone cells. Bran is nutritionally rich in protein and is used in the production of brown and wholemeal flours.
The wheat germ is the embryo that would eventually develop into the wheat plant. It is rich in certain vitamins, protein and oil. Consequently, it is often used in health foods, such as fortified bread and wholemeal flour.