Wheat Flour Milling, Second Edition
Durum wheat is milled to flour or to a granular endosperm product called semolina, which is used for the production of pasta products. Semolina differs from farina in that the latter can be produced from any wheat but semolina is made only from durum. Regulations by the U.S. Food and Drug Administration—FDA (2003) define farina as:
Food prepared by grinding and bolting cleaned wheat, other than durum wheat and red durum wheat, to such fineness that it passes through a No. 20 sieve, but not more than 3% passes through a No. 100 sieve. It is free from the bran coat, or bran coat and germ, to such an extent that the percent of ash therein, calculated to a moisture-free basis, is not more than 0.6%. Its moisture content is not more than 15%.
Semolina is defined similarly, except that it is made only of durum wheat, and its maximum dry ash content is 0.92%.
Durum wheat, which originated in the Mediterranean Basin, is also used in many of the surrounding countries for other local foods. Table 10-1 shows some major uses of durum wheat.
The durum kernel is usually vitreous and much harder than that of common hard wheat. When reduced to flour, the percentage of damaged starch from the endosperm is higher than for kernels of other wheats. This can be a very important factor in quality control, especially where durum flours are blended with other wheat flours.
It is more critical to achieve balance of the load to the different machines, especially the purifiers, when milling durum than when milling other varieties of wheat. Therefore, the miller must have a thorough understanding of the following basic factors: the pasta manufacturer's specific requirements; good wheat selection and handling procedures; efficiency in the cleaning house, conditioning and blending; grinding techniques; efficient stock classifications, sifting, and purification; and control of the environmental conditions in the milling facility. While these factors are important in processing all wheat flour, they are especially so in milling durum.