Potato cleaning with steam and flame method.
Steam cleaning of potatoes consists in subjecting them to a short-term action of steam under high pressure. This results in a superficial cooking and the tissue softening and relaxation. The steam peeling devices can be operated batchwise or continuously.
Drawing. The principle of operation of the mucus steam peeler: 1 - potato inlet, 2—A steam inlet, 3- steam outlet, 4 - outlet of peeled potatoes.
Potato losses during steam peeling are 19-24%, and including cleaning - approx. 25%. The disadvantage of this method is the formation of a dark ring under the surface of the potato, visible after cutting the tuber.
Flame cleaning of potatoes and vegetables is based on the surface firing of raw materials with exhaust gases (purulent aggregates), at a temperature of 1150-1200 ° C during 15-30 s, to carbonize the surface of potatoes or vegetables. Raw materials with a softer, the skin is not very sticky, it burns with exhaust gases at a temperature of approx. 900°C. Then the charred parts are rinsed with a stream of water of 2-3 MPa pressure. Raw material losses in this method are small and amount to 10-16%.
Drawing. Schematic diagram of a device for flame potato peeling: 1 - gear, 2 - base, 3 - shaft, 4 - rotor, 5—The rotary bottom of the furnace, 6 - chute, 7 - lower working chamber, 8 - thermal insulation, 9 - chamotte wall, 10 - gas burner, 11 - chute, 12 - upper gas chamber, 13 - conveyor, 14 - device cover, 15 - channel connecting the upper and lower working chamber, 16 - engine, 17 - scraper.
Chemical and thermal methods of purifying potatoes and vegetables are used primarily in the food and refrigeration industries. They can be used in very large gastronomic plants and in central preparation of potato and vegetable semi-finished products. Technological considerations determine the selection of the treatment method, economic, hygienic and the required organoleptic characteristics of cleaned potatoes and vegetables.