Cooking is recommended for products with bovine, swine, and poultry fat. The raw material is processed at a temperature ranging from 110°C to 135°C, usually using pressurized indirect steam. Water is separated from the already crushed and ground material by evaporation. Fat from the raw material itself is used, which liquefies upon being heated, helping the heat transfer. Batch or continuous digesters are used, and the heat transfer can be performed according to the type of digester (by discs, pipes, sleeve or heated). To increase the thermal efficiency and preserve product quality, it is possible to evaporate the water by means of a low temperature vacuum system, using special evaporators of the Slurry type.
