Abstract: Protein is extracted from fresh or cured pork bones to produce an aqueous solution of about 4% to 7% protein, as well as a lard by-product and cooked bone fragments which may be ground and sold as bone meal. Bone fragments of the desired maximum dimension are combined with substantially equal parts of water and are heated to above the boiling point of water when papain proteolytic enzymes are added in controlled proportions. The aqueous bone-enzyme mixture is heated in the 135.degree. F. to 145.degree. F. range for two hours when salt is added in controlled proportions followed by heating the mixture at 145.degree. F. for one hour and then rapidly heating the mixture for 5 to 10 minutes to 195.degree. F., then heating at, but not above, 195.degree. F. for 1/2 hour followed immediately by chilling as rapidly as possible to 150.degree. F. The solids are separated from the liquids and the liquids centrifuged to separate the lard product and aqueous protein solution.

Abstract: Protein is extracted from edible beef bones by crushing the bones to a predetermined size, then cooking the bones in approximately equal parts of water by weight with a papain based proteolytic enzyme added in a predetermined amount. Cooking is carried out for a total period of about 4-6 hours at stepped-up temperatures reaching up to but not in excess of about 195.degree. F. to avoid thermal shock to components. The cooked mixture is then filtered and screened to separate liquids from solids. The liquids then are centrifuged to separate the fats from the thus produced end product, a 4-7% solution of protein by weight. Thus three edible and salable products are produced without waste from the raw bone, i.e., gelatin bone, edible tallow or grease, and protein broth. The cooked material is held at about 150.degree. F. during filtering and centrifuging.