—The receivers of the oil should be either jacketed or have a boat bottom; that is, one vat placed inside of the other (see [Fig. 58]), so that the temperature of the oil in the receivers may be regulated, but under no conditions should steam pipes be submerged in oleo oil; all heating should be done by contact surfaces with hot water. In having the vat made with a boat bottom it is simply necessary to fill up the space with water and turn on steam, holding the water at the desired temperature.
Temperature of Oil Drawn to Tierce.
—The oil in the receiver, when ready to be tierced, should be raised to a temperature of from 116° to 118° F., and then drawn off, the tierces being filled through a side bung hole. After the tierce is filled it should be rolled away and left undisturbed in a temperature of 50° F. for at least four days. The oil thus handled will show a granulation, which is very desirable. If the oil is not allowed to stand until it has thoroughly granulated, or “seeded” it will come out smooth or pasty, and pasty oil is very objectionable to the purchaser. If the oil is not drawn off at this temperature it will be found difficult to have it seed properly, as it chills too quickly for a good granulation to take effect. It is not wise to draw the oil into a temperature lower than 50° F. After the oil has been seeded it can be kept in any storage that is available below 60° F., but it must be put into the refrigerating temperature for the first three or four days, and not at any time carried at a temperature below 45°.
Stearine.
—Stearine is the product left in the cloths after pressing the stock. This product is used for many purposes, but largely for the manufacture of compound lard on account of its hardness. (Ordinary tallow will run 41¹⁄₂ to 43; oleo oil runs 40 to 42; oleo stearine should run 50 to 52, titer.)
After the oil is thoroughly pressed out, the press is opened and the stearine taken out of the cloths. The stearine should be thrown into a bin where there is an abundant circulation of pure air, in order to thoroughly cool, for if it is put into the package too warm, a mold will form which deteriorates it and reduces its value. After it is thoroughly chilled it is put into packages, compressed by a machine as shown, which saves labor and puts more material into the package; or pounding it with a maul as it is deposited in the tierces.
FIG. 59.—STEARINE PACKER.
Stearine Storage.
—Stearine, after being put in packages, can be held for thirty days in ordinary storage. If held longer than that, it should be put into a room kept at a temperature of from 40° to 45° F. and which is perfectly dry. Stearine, generally speaking, is a very unsatisfactory article to carry any length of time, for, in pressing, any moisture which may be in the stock is left in the stearine, and if carried for some time this moisture produces a discoloration, which is known to the trade as “spotted stearine.” It also causes a moldy or musty smell, which injures it for edible purposes, and while it is often carried for months for an anticipated rise in the market, it is quite as often regretted that it was not sold when it was in good condition for the market.