Wet rendering
After size reduction in a crusher (mostly followed by a mincer), the raw material is melted in a cooker either with direct steam or indirect heat. To avoid damaging the nutritional values, this is carried out at the lowest temperature possible (70-90°C). The separation of the three phases (solids, aqueous phase and melted fat) can be achieved by different techniques. The most common is drainage of the solid phase, which is subsequently pressed and dried. The liquid phase is sent to a decanter (horizontal centrifuge) or tricanter. Decanters separate two phases, tricanters three phases in one step. Solids from the decanter are dried together with the other solid phase. The liquid phase, the so-called stick water, is sent to the dryer, either directly or after a concentration step in an evaporation unit. In some cases the liquid phase is concentrated and dried separately into high-value, highly digestible proteins. The fat is cleaned.