What Is Meat Rendering?

Meat rendering uses animal waste materials to produce tallow, grease and high-protein meat and bone meal. Edible rendering plants use animal waste to produce fats and proteins for consumption. These plants operate in conjunction with meat packing plants under the oversight of the U.S. Department of Agriculture and the Food Safety and Inspection Service.

Tallow Processing

• Rendering animal fat trimmings to produce tallow begins by grinding the trimmings and then melting them in a melt tank. Melted trimmings go through a disintegrator to rupture fat cells. A centrifuge separates edible fat from an inedible sludge that contains water and leftover substances.

Batch Rendering

• Batch rendering is the process used to produce bone meal. This process crushes animal trimmings so they're easier to cook. After cooking, the trimmings go to a percolator drain pan that contains a screen to separate liquid fat from protein solids. Protein solids go through a screw press to take out any remaining fat. The remaining protein solids, called crackling, go through grinding and screening to produce meal.

Grease Processing

• Another meat rendering process recycles cooking grease from restaurants. After grease arrives at a rendering plant, it goes through a screen to remove solid materials. It's heated and stored in a processing tank where gravity separates grease, emulsion, water and solids. Centrifuges remove remaining water and solids from the emulsion.