CHAPTER IX.

MANUFACTURE OF OLEOMARGARINE AND LARD-COMPOUND.

Utilization of Cottonseed-oil for Edible Purposes. Manufacture of Oleostearin and Oleo-oil. Manufacture of Neutral Lard. Manufacture of Oleomargarine: Historical; Apparatus; Ingredients; Use of Cottonseedoil; Procedure of Manufacture. Manufacture of Lard-compound: Ingredients; Manufacture of Lard-stearin. Mixing. Some Fertilizer History.

Utilization of Cottonseed-oil for Edible Purposes.-The perfect edibility of refined cottonseed-oil permits its use for every purpose for which animal fats are commonly used. Its most important use for edible purposes is in the manufacture of a substitute for the fat of swine, or lard. This substitute has come to be known as lardcompound. It consists of summer white cottonseed-oil and oleostearin mixed in various proportions, and sometimes with a small percentage of genuine lard. The use of next importance is in the manufacture of a substitute for butter. This product is commonly called oleomargarine. It is made in various grades according to the proportions of the different ingredients used. The characteristic ingredients are oleo-oil and neutral lard, with varying amounts of summer yellow cottonseed-oil according to the quality of the finished product, together with milk, salt, and coloring-matter. In grades of superior quality some butter may be used.

Important direct uses of refined cottonseed-oil are: as a table or salad oil, for which winter yellow oil is commonly used; for packing sardines, for which summer yellow oil is used; and as a complete or partial substitute for many purposes for which olive-oil is used.

Manufacture of Oleo-stearin and Oleo-oil.-Oleo-stearin is the base of lard-compound; oleo-oil with neutral lard is the base of oleomargarine. They are obtained from choice beef fat by a process of

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heating the finely divided fat in open kettles, removing and washing the liquid fat to separate the tissue; then crystallizing the fat and subjecting it to pressure whereby the oleo-oil separates as a liquid, leaving the stearin as a solid fat.

After the animal is slaughtered the fat is removed and placed in a vat of warm water, where it is thoroughly washed to remove blood and adhering impurities. It is then chilled and hardened with a bath of ice-water, after which it is finely comminuted by cutting-machines and melted in steam-jacketed caldrons at a temperature of about 160° Fahr. Slowly revolving agitators keep the fat moving until the melting process is complete, when the whole is allowed to settle. Fig. 58 represents a car of comminuted fat from the cutting-machine being dumped into the melting-kettle. The settling process is accelerated by the addition of salt, which is scattered over the entire surface of the liquid and settles the fibre or "scrap" to the bottom. After the first settling the clear oil is carefully siphoned to a second series of jacketed caldrons, usually on the floor below, where more salt is added, and the temperature controlled until a second settling is completed. This demembranized fat is now siphoned into mounted vats and allowed to stand from three to five days in a temperature favorable to the crystallization of the stearin, a part of which forms a crust over the top and the remainder settles to the bottom, leaving the clear oil between. It is a common phenomenon in the crystallization of various substances whose specific gravity is not greatly in excess of the motherliquor that, cooling first at the top, a portion of the substance which is being crystallized out forms a crust over the surface and the remaining portion is precipitated. When the vats have stood the required time the crust is broken into fine particles and the whole is given a thorough mechanical mixing, which leaves it of a mushy consistency. It is then wheeled to a revolving table surrounded by skilled workmen, who wrap the mixture into small packages with canvas cloths, each containing about three pounds, which are built into the presses. The oleo-oil is then separated by great pressure, slowly and gradually applied, and flows from the presses into a large receiving-tank on the floor below, from which it is piped to the oleomargarine department or is drawn into new oak tierces

and allowed to harden in preparation for shipment to independent manufacturers or for export. Fig. 59 shows two presses, one filled and the other in process of being filled.

All manufacturers of oleo-oil follow substantially the method above described, but the system of grading and the character of the fat selected differ greatly. The number of grades manufactured is from three to five, and when the market is active and prices are high, about all the fat taken in slaughtering, both from cattle and sheep, is worked into one grade or another. The oil made

from sheep fat cannot be neutralized. It retains the characteristic odor and flavor of the animal to such degree as to be unfit for the oleomargarine demanded in American markets. It is exported to Europe, where there is demand for cheaper oils. With the beef fats the character of the animal from which they are taken is the most potent factor in the selection. Some manufacturers work

FIG. 59.-Separating Oleo-oil from Stearin of the Fat by Pressure. into their highest grade of oleo-oil practically all the fat taken from a good steer and make one or two lower grades from the fat of cows and "canners." Other manufacturers make their highest grade from the caul and other selected fats of the best beeves, using certain intestinal and other lower forms, together with that taken from poorer animals, in making from one to three lower grades. The quantity of oleo-oil obtained by the process described is, by weight, about 50 per cent. of the fat treated. About 28 per cent. is stearin and the remainder is shrinkage. The quantity obtained from each beef is difficult of exact determination because it varies so greatly with size and condition of the animal when slaughtered.

Manufacture of Neutral Lard.-Neutral lard is composed of the fat derived from the leaf of the slaughtered animal, taken in a perfectly fresh state. Two grades are made one from the leaf, the other from the back fat of the hog. Its manufacture is almost exclusively confined to large packing-houses, but there are independent manufacturers of oleomargarine located near the packing centres who prefer to buy the fat as it is taken from the animal and work it into neutral by their own process. In the packing plants the leaf fat is taken from the animal immediately after killing, hung on mounted racks, and wheeled into refrigerators to remove as quickly. as possible all animal heat. It is next chopped finely or reduced to pulp by machinery and melted in jacketed kettles exactly similar to those used for oleo-oil. When the melting process is complete it is allowed to settle, the precipitation of the fibre being accelerated by the addition of salt as in the case of oleo-oil. After the settling process the clear oil is siphoned to a receiving-tank, and what is not used in oleomargarine is tierced for shipment. A good quality of leaf fat will produce by careful handling about 90 per cent. of its weight in neutral, and each animal will yield an average of eight or nine pounds. Comparatively little neutral is made from back fat. The amount used, however, depends much on the relative demand for neutral and ordinary lard products, as it is sometimes more advantageous to work fats into one form than another. The oil made from back fat retains more of the flavor peculiar to lard and, like the lower grades of oleo-oil, is less free from stearin or other undesirable constituents. Some packing-houses mix a small per cent. of back fat with the “leaf” in making their highest grade of neutral, and oleomargarine manufacturers sometimes use both grades of the finished oil in combination. The difference in price between the two is usually slight, and neutral made exclusively from "leaf" is generally sought. Independent manufacturers of oleomargarine, who make their own neutral lard, give the fat a more extended treatment than that described as the process of the packers. In addition to the separation of the fibre by the process of settling the clear oil is drawn into a large vat of salt water at a low temperature, where it is again chilled and hardened, and is allowed to remain for several hours. It is then placed on shelves to drain