Pretreatment process for rendering

Abstract

A rendering system and method is provided for the rendering of organic materials into its major components comprising water, fat and solid proteins. The process involves mixing additional fat with the raw material to form a pumpable slurry including fat and water emulsions. The slurry is treated to break the emulsions and insolubilize the protein solids wherein the fat becomes a continuous phase fat in the slurry and the water becomes a continuous phase water. The treating comprises adding fat to the raw material having a temperature within the range of 140.degree. F. to 270.degree. F. in an amount such that the ratio of added fat to the dry defatted solids of the slurry is in the range of 4 to 1 to 6 to 1, respectively. The treating further includes partially drying the slurry such that at least 15 percent by weight of water as measured as a percentage of total water and defatted solids remains with the solids which discharge from the partial drying step as part of the partially dried slurry. The treated slurry is centrifuged to split the slurry into at least two streams, a first stream comprising wet solids and a second stream comprising fat. The fat contains less than 0.2 percent insoluble solids. The wet solids are dried and produced as a finished product with less than 6 percent residual fat.