Method of producing stabilized bone

#The invention relates generally to cleaning and stabilizing bone for producing gelatin, glue and similar proteins, and, more particularly, to a continuous process of preparing low fat clean stabilized bone of improved quality which is adapted for producing high quality gelatin and glue.

#Bones, such as cattle and hog bones, contain substantial amounts of collagen and have long been used for making gelatin, glue and other protein products. In view of the decreasing availability of naturally dried bleached bone from India trimmed raw bone from meat packing plants and boning plants where carcasses are trimmed to remove most of the useful meat tissue and fat is becoming an increasingly important source of bone for making high quality gelatin and glue. The trimmed raw bone, however, contains considerably more fat and meat tissue than can be tolerated when the bone is used for making gelatin or glue, and the bone must be cleaned before it can be used for making gelatin or glue by separating fat and meat tissue from the bone.

#As the bone material frequently must be held for an extended period under conditions which are conducive to spoilage before being used, the raw bone must also be stabilized so that it is capable of prolonged storage under ambient conditions without developing objectionable odors, discoloring or being attacked by bacteria, fungus or other microorganisms. In order to stabilize raw bone so that it does not develop the latter objectionable characteristics while being transported or stored, it has been found necessary to not only remove fat and meat tissue from the bone but also to heat the bone to a temperature over 180.degree. F. to effect a kill temperature for any microorganisms present in the bone and reduce the moisture content of the bone to a level which does not support growth of microorganisms which come into contact with the bone.

#Other objects of the present invention will be apparent from the detailed description and claims to follow when read in conjunction with the accompanying drawing comprising a block flow diagram illustrating the preferred process of the present invention.

#A continuous process for producing clean stabilized bone of improved quality is provided in accordance with the present invention, and in general the process preferably comprises depositing raw trimmed bone as received from a meat packing plant or boning plant into a receiving bin or pit and continuously conveying the bone material by a screw conveyor or like means from the receiving bin to a pre-hogger where tramp metal is removed and the bone reduced in size from its natural state to pieces preferably ranging between about 1 and 6 inches in length suitable for feeding into a press. The bone leaving the pre-hogger is in the form of a flowable mixture containing bone, bone marrow, fat, meat tissue and liquid in the form of blood, body fluids and moisture. From the pre-hogger the bone and adhering fat and meat tissue are then fed continuously into a press, preferably a screw type press, mounted within a cage or casing having perforations or small openings in a wall thereof. The screw press preferably has a coke mounted at the discharge end for controlling the pressure applied to the bone within the cage so that sufficient pressure is applied to the raw bone in the press to force a substantial amount of the soft non-bone material, such as the fat and meat tissue which comprises muscle tissue, sinew, cartilage, tendons, etc., along with considerable liquid contained in the raw trimmed bone material and with a minor amount of small bone particles through the perforation or narrow openings in the cage and discharges the pressed bone material from the press separately from the non-bone material in a form which can be readily dried. The pressed bone material as discharged from the press has a substantially uniform composition with an average fat content at lease about 3 percent by weight and containing generally about 12 percent by wt. meat tissue and having a moisture content of about 25 percent by wt. regardless of the amount of fat, meat tussue and moisture in the raw trimmed bone material fed to the press. The uniformity in the composition of the pressed bone material as discharged from the press permits continuous economical production of uniformly high quality stabilized bone material.

#The pressed bone stripped of a substantial portion of the fat, meat tissue and moisture and, while reduced to a size suitable for passing into and through an oven dryer, is preferably conveyed by suitable means to a crusher mill, such as a hammer-mill, which further reduces the size of the bone particles without, however, fine grinding or otherwise reducing a substantial portion of the bone to a particle size below about 1/8 inch. The bone from the crusher mill preferably has an average particle size of about one half inch.

#The pressed raw bone as discharged directly from the press or from the crusher mill is continuously fed into an oven dryer in which the pressed raw bone material is heated until the pieces of fat and meat tissue adhering to the bone particles are crisped so that the pieces of fat and meat tissue are readily fractured and separated from the bone particles entirely by mechanical attrition during the further processing of the bone material in the screening, conveying and gravity separation treatment thereof. The oven heating or baking step which effecs crisping also inherently reduces the moisture content of the bone below 10 percent by wt. and preferably below about 5 percent by weight. The oven dryer is preferably an oven from which air is excluded as a result of heating the bone and vaporizing moisture in the pressed bone feed material, preferably to a maximum temperature of about 250.degree. F. (121.degree. C.), to provide an atmosphere of dry superheated steam within the oven.