Pearling process of cereal

Milling represents the principal procedure in the cereal industry and is classified in two categories: dry and wet, while each has its own characteristics. Dry milling separates the outer fibrous materials and germ, which are considered by-products of the grain endosperm.

Dry milling can also refer to pearling. Pearling is the process, prior to milling that with the application of abrasion and friction removes effectively only the bran layers from the cereal grains (rice, oat and barley), allowing nutritious parts, such as the aleurone layer to remain in the intact kernels. This pre-treatment potentially could also improve milling yields of superior flour quality.

The industry also uses this technology in wheat flour milling because it lowers the capital investment costs, giving the benefit of better-quality products. Removal of the outer kernel layers to a desired level prior to milling means less bran to be removed during the subsequent milling process, fewer stages, and better flour and semolina yield.

The by-products of the pearling process, ≈30–40% of the total kernel weight, are mainly used in animal feed. These by-products contain interesting amounts of bioactive compounds such as β glucans, tocopherols, and tocotrienols.
Pearling process of cereal