Page:Foods and their adulteration; origin, manufacture, and composition of food products; description of common adulterations, food standards, and national food laws and regulations (IA foodstheiradulte02wile).pdf/105

 used for any purpose whatever and their carcasses are to be buried so as to remove all danger of infection.

Brown Grease.—Brown grease is a product of a lower grade than white grease and is made usually by rendering the whole animal. It is one of the by-products in the manufacture of tankage from condemned animal carcasses, the tankage being used as fertilizer. Both white and brown grease are used chiefly in the manufacture of low grade lard oil and in the making of soap.

Yellow Grease.—Yellow grease is a product intermediate in value between white and brown grease. It is made chiefly from the carcasses of animals that die while on the packers' hands. It is used for the same purpose as white and brown grease.

Pig's-foot Grease.—A special variety of grease is made from pigs' feet as a by-product in the glue factory. This grease is used also in making lard oil and soap. It is evident that these varieties of grease are only inedible varieties of lard, and through proper inspection the public is protected against the use of these varieties of grease in the edible product.

Lard Stearin.—Mention has already been made of the fact that by melting a fat and cooling it slowly towards its solidifying point, certain constituents of the fat which have a higher melting point separate first, leaving those constituents with a lower melting point still in a liquid condition. Those portions of an oil or fat which separate first under such conditions, are the constituents of the product which is known as stearin, while the part that remains liquid is the constituent known as olein. Lard stearin is made principally for the manufacture of mixtures and is a by-product of the highest grade of lard oil. Lard stearin is made as follows: The lard is melted and kept in a crystallizing room at from 50 to 60 degrees F., until it is filled with the crystals of the separated stearin. The product is then wrapped in the form of cakes with cloth. Each package contains from 10 to 20 pounds. The cakes are then placed in a large press with suitable arrangements to facilitate the escape of the oil and maintain the low temperature. The pressure is applied very gradually at first, and as the process advances, with increasing power. The high grade oil obtained in this way is known as prime or extra lard oil and is used for illuminating and lubricating purposes. The resulting solid product, which is principally stearin, is used as one of the adulterants of lard, that is, in making a mixture which is sometimes called lard, composed of lard stearin and cottonseed oil.

Tanks Used for Producing Lard Under Pressure.—There are various forms of tanks used for producing steam rendered lard. In the open kettle there is a jacketed arrangement by means of which steam, at the proper temperature, is made to act upon the contents of the inner kettle. In the closed kettle the steam may be applied in the form of a jacketed arrange-