A heating installation for baking bread products; it is the most important piece of equipment used in commercial baking. A baking oven consists of a source of heat, a baking chamber usually equipped with a steam humidifier, a conveyor with facilities for loading the dough and unloading the bread, an automatic regulating system for the baking process, and a device to recover the heat of lost gases. The average temperature in the baking chamber is 200°–300°C, and the relative humidity is 15–70 percent. With respect to the nature of the working process and the equipment, baking ovens are similar to confectionery ovens.
Baking ovens are classified as batch or continuous ovens, depending on the method of operation, and as conventional and pass-through types (single-level and multilevel), depending on the design of the baking chamber. In conventional ovens the pieces of dough are loaded and the baked goods removed from the same side; in pass-through ovens the operations are performed from opposite sides. Ovens are also classified by the type of hearth. They may have cradle hearths suspended from a chain conveyor, plates mounted on a chain conveyor that form a continuous horizontal hearth, a lattice hearth in the form of a belt conveyor, a disk rotating about a vertical axis, a ring, or a draw plate or fixed sole hearth.
Baking ovens are also classified according to the means used to heat the baking chamber. They may have tubular sections to which high-pressure saturated steam or superheated water is supplied, flat or tubular channels through which the combustion products of a fuel and recirculated gases are passed, or a baking chamber heated directly by electric heaters, gas burners, or infrared radiation lamps. Some use a combination of heating methods.
Baking ovens may be mechanized to various degrees. In automated ovens with conveyor hearths, the conveyor travel, heating conditions, and steam supply are automatically regulated, and the loading of dough pieces and unloading of the bread are mechanized or automated; provision is made for an automatic device to ensure safe fuel combustion. In mechanized ovens with conveyor hearths, the conveyor travel is regulated, the unloading of the finished goods is mechanized, and provision is made for an automatic device to ensure safe fuel combustion. Other mechanized ovens have disk or extensible hearths; they are being supplanted by more modern designs. Nonmechanized ovens are used only in small enterprises.
The branch of the food-processing industry that produces various types of bread, rolls and baranki products, therapeutic and dietary baked goods, and enriched and un-enriched biscuits. The variety of products offered is great. In the USSR in 1975, the baking industry produced more than 15 percent of the total gross output and used 8 percent of the total fixed production assets of the food-processing industry. The basic raw material used by the baking industry—flour—easily lends itself to transportation, but the finished products do not. Prolonged storage of most baked goods is impossible because of staling; as a result, production conforms to the daily requirements of retail outlets, which vary in quantity and assortment.
By the beginning of World War I, prerevolutionary Russia had several large, mechanized baking enterprises in St. Petersburg, Moscow, Kiev, Odessa, and Kronstadt; however, small cottage bakeries predominated. The establishment of a modern baking industry in the USSR began with the construction of large bakeries in the 1930’s. The production base of the industry is being continually expanded by the construction of new enterprises and the reconstruction of existing ones. Approximately 30 large-scale state bakeries are put into service annually, as well as 250 mechanized small-scale bakeries of the Central Cooperative Alliance in rural regions. Between 1956 and 1975 alone, more than 850 large-scale bakeries were constructed. By the beginning of 1976, there were approximately 16,000 enterprises in the baking industry, including more than 5,000 state enterprises and approximately 11,000 cooperative enterprises; they employed more than 510,000 people. The average daily capacity of a bakery rose from 18 tons in 1940 to 54 tons in 1975. Annual bread production (in million tons) was 2.4 in 1928, 24 in 1940, 24.3 in 1960, 32.3 in 1970, and 33.5 in 1975 (excluding home baking).
Production in the baking industry in the USSR is highly concentrated. Of the total volume of bread baking in 1976, 20.5 million tons was produced in 2,700 large-scale bakeries. Major trends in the technological progress of the industry include the integrated mechanization and automation of bread production, transportation, and storage; the introduction of new technology; the development of continuous production lines for the preparation and shaping of the dough; and the baking of bread in high-efficiency conveyor ovens with automatic control. The Soviet baking industry receives more than 20,000 units of production equipment annually. In 1975 there were more than 8,000 production lines and mechanized production lines in operation, of which more than 1,700 featured integrated mechanization. Equipment has been introduced into bakeries for the bulk transportation and storage of flour and other ingredients, such as salt, liquid shortening, and sugar syrup; in 1976, 39 percent of the total volume of flour was handled in this manner, according to the Ministry of the Food-processing Industry of the USSR.In 1974 the level of mechanization of production in the enterprises of the Ministry of the Food-processing Industry of the USSR was as follows: 90 percent in the production of pan bread, 75 percent for hearth bread, 64 percent for small items sold by the piece, 51 percent for enriched products, 74 percent for baranki products, and 55 percent for enriched biscuits. Approximately 10 million tons (about 50 percent) of the output was produced by new production systems. In 1976, 65 percent of the bread produced was made with graded wheat flour, compared with 44.5 percent in 1953. The variety of products offered is substantially increasing, and the quality of bread and rolls is improving, especially the production of high-quality loaves, small rolls, pastries, cakes, enriched biscuits, and baranki products. The output of rolls made with patent flour increased by a factor of 1.5 from 1971 to 1975. In other socialist countries the baking industry is developing at a rapid pace. Mechanized bakeries are being constructed and many have been put into operation. Specialized enterprises are being established, as well as enterprises producing both baked goods and other food products. In Czechoslovakia, for example, some baking enterprises are combined with confectionery and macaroni enterprises. Among the capitalist countries there is a very high level of mechanization and automation in the baking industries of the USA, Great Britain, Canada, France, the Federal Republic of Germany, and the Netherlands. The production of equipment for the baking industry is most highly developed in the USA, Great Britain, the Netherlands, and the Federal Republic of Germany.