Semolina is the coarse, purified wheat middlings of durum wheat used in making pasta, breakfast cereals, puddings, and couscous. The term semolina is also used to designate coarse middlings from other varieties of wheat, and from other grains, such as rice and maize.
Modern milling of wheat into flour is a process that employs grooved steel rollers. The rollers are adjusted so that the space between them is slightly narrower than the width of the wheat kernels. As the wheat is fed into the mill, the rollers flake off the bran and germ while the starch (or endosperm) is cracked into coarse pieces in the process. Through sifting, these endosperm particles, the semolina, are separated from the bran. The semolina is then ground into flour. This greatly simplifies the process of separating the endosperm from the bran and germ, as well as making it possible to separate the endosperm into different grades because the inner part of the endosperm tends to break down into smaller pieces than the outer part. Different grades of flour can thus be produced.