Curing Oven

an installation for smoking fish, meats, and other food products. There are chamber and span ovens (periodic operation) and tunnel and tower ovens (continuous operation) for hot and cold smoking of fish. The food products are loaded into the curing oven on carts and in boxes or on conveyors and are suspended on metal arms, racks, and hooks or placed on grids. Large products are tied with twine. In chamber curing ovens the product is loaded and unloaded periodically from one side; in tunnel ovens the product enters and leaves on opposite sides and moves horizontally; in tower ovens it moves from bottom to top and back again, or vice versa; and in rotary ovens it usually moves from top to bottom in a spiral.

The processing offish in curing ovens is done in stages: drying, cooking (for hot curing), curing, and cooling. The drying is done by circulating air, and the cooking is done by hot air heated by steam or electric air heaters. The cooking may also be done by infrared radiation. The curing is done by smoke that forms during incomplete combustion of sawdust and wood. Ventilators circulate and discharge the smoke from the oven. The time and temperature of smoking depend on the method of curing being used. Before entering the curing zone the smoke passes through filters that remove carcinogenic substances.

The use of electric curing devices is promising. In this case the curing is done in three stages: drying, smoking, and baking. Small and medium fish are dried and baked by infrared radiation. Vertical electric smoking ovens are composed of a system of three shafts with a conveyor and electrical devices. The fish are strung on metal rods and loaded onto a conveyor. They are dried by infrared lights (or panels) in a chamber and pass into a smoke shaft. Smoke from a smoke generator is drawn naturally into a high-voltage electric field, where ionization takes place, the particles become charged, and the smoke settles on the surface of the fish. Then the fish enters the thermal treatment shaft, where baking and associated processes take place under three sections of infrared lights. The finished product is fed into a shaft, where it cools, and then it is removed from the rods at the unloading window. Electric curing is very economical because of the reduced consumption of raw materials and fuel.