Abstract: A method for rendering animal materials is provided that includes the steps of providing one or more animal materials, and applying an amount of a chelating solution to the animal materials prior to heating the materials in a cooker. The method further includes the step of heating the materials to thereby release at least some water and fat from the material, and then pressing the materials to further release water and fat from the materials. An antioxidant composition is further applied to the materials to provide rendered animal materials having an increased quality and long-term stability.

Abstract: A combination of entirely natural antioxidants provides an unexpected synergistic effect in extending the shelf life of animal-fat-containing feed when admixed with such fat or feed in amounts which are economically feasible. The specific antioxidants are lecithin, tocopherol and oil of rosemary. All combinations of at least two of these in amounts of from 0.01 to 2.0 percent by weight of lecithin, from 0.0035 to 0.056 percent by weight of tocopherol and from 0.01 to 0.10 percent by weight of oil of rosemary (based on the combined weight of antioxidant and animal fat) inordinately extend the shelf life of animal feed in general and of pet food in particular, when such products contain animal fat.