a branch of the food industry, the manufacture of groats and groat products from different grains.
The basis of the production process of groats is the mechanical separation of the grain’s cover tissues, or hull, and the subsequent processing of the kernel and cotyledons. The method of hulling is determined by the anatomical characteristics of the grain (for example, the strength of the kernel and the hull and how the hull is attached to the kernel). Successful processing of the grain is possible only with a moisture content of 13-15.5 percent. The production process generally consists of removing impurities from the grain, sizing, shelling (removal of the hulls), processing of the kernel (crushing, grinding, polishing, or rolling depending on the type of grain and the sort of groat to be obtained).
Many plants that manufacture groats are equipped with additional equipment and have a more involved method of processing. For example, after the removal of the impurities, the raw material is subjected to hydrothermal processing (moistening in water or steam and subsequent drying). This process increases the strength of the kernel, and the hulls become more brittle and are easier to remove. Hydrothermal processing also increases the groats’ shelf life.
The impurities of the grain are removed by aspirators, separators, sifters, stoners, hullers or magnetic separators; the grain is then graded on sorters. Depending on the type of grain, various types of hulling machines are used. The hulls of buckwheat and millet grain are easily separated on shellers; rice grain is hulled by various hulling mills. After hulling, the product is winnowed. The insufficiently scoured grains are again passed through the machines and then ground in order to remove the remnants of the glumes, the fruit and seed coverings, and the embryos. These processes improve the appearance, cooking qualities, and digestibility of the groats. Certain types and varieties of groats, such as peas, rice, and pearl barley, are polished on special machines. The finished product is sorted by size. For example, there are five sizes of barley and corn groats, four sizes of Poltava, and three sizes of pearl-barley groats.
In the mechanical processes of cleaning and particularly of hulling and grinding, the kernels of some of the grains are crushed, lowering the quality of the product. Thus, both buck-wheat groats (the whole kernel) and the less valuable ground buckwheat are obtained from the processing of buckwheat grain. The side products and wastes such as chaff and flour (meal) are used for feed or industrial purposes. The husk is a waste product of little value; it is used for fuel, for producing furfural, and for other needs.
The groat yield, that is, the percentage of groats obtained from the processed grain, depends on the grain properties, such as size, regularity, and the amount of good-quality kernels; in glume crops (rice, barley, buckwheat, millet) the yield depends also on the content of glumes. For example, 68.5 percent millet grain is obtained from millet, and 60 percent buckwheat groats and 10 percent buckwheat flour are obtained from buckwheat.
In the USSR, by equipping enterprises for the production of groats with new machinery and by automating production, the methods of manufacturing groats have steadily improved. The quality and nutritional value have been raised, the assortment has been expanded, and the cooking time has been reduced. Ready-to-eat groats have also been developed, such as corn-flakes, buckwheat flakes, puffed wheat, puffed rice, and popcorn. These ready-to-eat products are produced by special processing, which includes cooking in malt, sugar, and salt syrups, steaming, rolling, baking in ovens (cornflakes), and heating under pressure in special equipment (puffed grains).
REFERENCESTovarovedenie zerna iproduktov ego pererabotki, 2nd ed. Moscow, 1971.
Tekhnologiia pererabotki zerna. (Mukomol’noe, krupianoe i kombikormovoe proizvodstvo). Edited by la. N. Kuprits. Moscow, 1965.
Zhislin, la. M. Tekhnologiia i oborudovanie krupianogo proizvodstva. Moscow, 1966.
Trisviatskii, L. A., N. V. Saburov, and B. V. Lesik. Khranenie i tekhnologiia sel’skokhoziaistvennykh produktov. Moscow, 1969.
L. A. TRISVIATSKII