CHAPTER XXIII.LARD, COMPOUND AND GREASES

Historical — Quantity and Quality — Neutral Lard — Kettle Rendered Lard — Prime Steam Lard — Refined Lard — Bleaching Lard — Filter Press — Lard Roll — Lard Packing — Compound Lard — Cottonseed Oil — Refining Crude Oil — Deodorizing Cottonseed Oil — Pressing Temperatures — Lard Oil — Treatment for Lard Grease.

—The refining of lard in packing houses is comparatively recent, and many people will be surprised to know that even the largest packers only added lard refining to their business within the past twenty-five to thirty years. Previous to that time lard refineries were operated by independent firms, who bought their supply of prime “steam” lard, converting it into the different grades in their own establishments. In the natural evolution of the business this branch was taken up by the packers.

Before the advent of present methods, lard refining consisted in pressing from the lard about 30 to 40 per cent lard oil, sold for lubricating and lighting purposes, etc., and mixing the stearine with straight lard, making a high grade pure lard. At this time the method of bleaching in all lard refineries was accomplished by the use of caustic soda, pearl ash, lime, alum, or other substances, the principal ingredient, being caustic soda. The underlying principle is that alkali, used in proper proportion, saponified the acid in the lard. This process, however, is a thing of the past.

—As shown in a previous chapter from thirteen to fifteen percent of the live weight of the hog is fresh lard, consequently where large numbers of hogs are killed the manufacture of lard is an important factor in thepacking business. The principal grades are known as neutral lard, kettle rendered lard, prime steam lard, refined lard and compound lard.

Tallow and stearine also enter into the manufacture of refined and compound lards.

—When oleomargarine was first manufactured it was considered necessary to use natural butter in the mixture in order to give it the proper consistency, as the oleo oil was grainy and coarse, therefore sufficient natural butter was added to change that condition. Some one conceived the idea of using neutral lard made from leaf lard in place of natural butter in oleomargarine. When this was worked out successfully the term oleomargarine practically disappeared and the term “butterine” was substituted. In most of the butterine made today no natural butter is used.

The conditions in making oleo oil and tallows have their parallel in neutral lard and kettle rendered lard. When leaf lard is cooked for kettle rendered lard, if a temperature of from 250° to 260° F. is obtained the tissues of the lard are burned or partially consumed, this heat giving it a flavor which is called “high kettle rendered” flavor. When it is made into neutral this condition is reversed, the lard being melted at a temperature of from 126° to 128° F. At this temperature no burning of tissues is possible, hence the oil extract is neutral in every sense of the word, in color, flavor and smell. With these three essential points the material readily forms the chief substance for butterine by adding milk or cream and oleo oil and cotton seed oil, as desired.

—The following steps define the process of manufacture necessary to produce neutral:

—The leaves as pulled from the hogs are rapidly sent to a cooling room to be thoroughly chilled. The leaves are spread separately in flat sheets on metal supports, which are preferable to wood. If it is chilled too slowly a strong “hoggy” flavor is developed, which it is impossible to eradicate from the fresh product. The leaf lard should be chilled for twenty-four hours in a temperature of 32° to 34° F.

—It is put through a hasher of the Enterprise type to an open top water jacketed kettle, similar in type to an oleokettle. Frequently the melting kettle is a wooden vat with a galvanized iron kettle inside, the space between the wooden vat and the galvanized kettle being filled with water which is heated to the desired temperature for melting the product. It is not practicable to use a steam jacket as the heat would be excessive and it would be difficult to control. This kettle properly is water jacketed and open top so no pressure is generated.

In a kettle holding 4,000 to 5,000 pounds, water should be warmed in the jacket before lard is put in, the agitator started slowly, not to exceed 10 to 12 revolutions per minute, and the heat should be regulated so as to have the lard all melted and ready to drop in one and one-half hours from the time of starting to hash. By the time the lard is thoroughly melted the temperature should be 126° to 128° F.

—As soon as the lard is melted it should be drawn off with a siphon into receiving kettles, which are also jacketed and held at practically the same temperature. When dropped it should be salted with one-half to one per cent of fine salt, letting it stand from fifteen to thirty minutes. In drawing off it should be siphoned through several layers of cheese cloth, forming a strainer, into receiving tanks, where it should settle four hours. It is drawn into tierces through a pipe raised from the bottom to leave one and one-half to two inches of lard in the tank, care being taken that no “bottoms” are drawn into the tierce, as these contain tissues which are, for the most part, undiscernible; also moisture. These ingredients in neutral, being only partially cooked, immediately begin to decompose. It is a delicate article to handle and the settling of all impurities is important. The neutral, when drawn into tierces, should be at a temperature of from 115° to 118° F.

—The tierced lard should be kept at a temperature of about 75° F. for about ten or fifteen hours, and then put into a cooler with a temperature of from 45° to 50° F. The tierces should be filled through the bilge and not closed when stored in the first mentioned temperature, the bungs being left out, while the heat is permitted to escape, thus carrying with it considerable flavor, and making the material more neutral than if the tierces were closed as soon as filled.

—This is a neutral lard made from back fat. At times it is profitable to make this product into No. 2 neutral instead of steam lard, for when the market for No. 1 neutral is extremely high there is demand for a good No. 2. When making this, the rind should be skinned off from the back fat, leaving clear back fat to be hashed for neutral. If the rinds are put in, it gives the product a “hoggy” flavor, which makes it undesirable. It is hashed and melted the same as No. 1 neutral, except as to temperature, the melting point for this being 132° to 134° F., method and apparatus as described for the making of No. 1 neutral, being applicable to this.

—Below is a test on raw leaf lard rendered into neutral, showing yield, and percentage of the neutral lard produced; the scrap and bottoms from the kettle being run into kettle rendered lard.

TEST ON LEAF LARD RENDERED INTO NEUTRAL.

—

TEST ON CHILLED LEAF LARD TO DETERMINE VALUE AND YIELD.

—Showing manipulation of 5,000 pounds of back fat to make neutral, kettle rendered lard and pure steamed lard:

TEST ON 5,000 POUNDS OF BACK FAT CONVERTED TO NO. 2 NEUTRAL KETTLE RENDERED LARD AND PRIME STEAM LARD.

RECAPITULATION.

—Kettle rendered lard is the purest and best lard made in packing houses and consists of leaf lard and back fat, the proportions varying according to the value of the raw product, usually on a basis of about 60 per cent back fat and 40 per cent leaf. While kettle rendered lard is sold under the label of “pure leaf lard” there is little leaf used, as this part is worth more as a neutral lard than when made into kettle rendered. A very acceptable formula for kettle rendered lard, if handled properly, is as follows:

Where neutral lard and kettle rendered lard are made together a nice flavor may be imparted to the kettle rendered lard by using the bottoms of neutral lard when cooking it, as the scrap from the neutral when brought to the high temperature of kettle rendered lard imparts a rich flavor.

—The raw product is put through a hasher which cuts the fat tissues, so that when the heat is applied the oil readily separates. The kettle generally used for this purpose is about five feet in diameter and from five to seven feet deep, made of wrought iron, jacketed for steam, with an agitator to keep the product agitated while cooking. The jacket should be kept heated until through hashing, then increased until the temperature of the lard reaches 255° to 260° F., when the pressure should be shut off for one and one-half hours at least—one and one-half hours should be taken to reach this period. If lard stearine is used it should be added at this time, using about 15 per centfor the summer formula. After this period of shut-off, again turn on the steam, holding temperature, allowing the contents to cook until dry, or until no further steam arises, which will consume probably from thirty to forty-five minutes. Stop agitating and add twenty pounds of salt, let stand to settle one hour, then lower into the kettle below, strain through a cloth sieve, the lard being taken off the scrap with a siphon. The scrap will remain in the bottom of the cooking kettle; if handled carefully, very little will pass through the pipe. The lard, when being drawn into the kettle below, should be passed through several thicknesses of cheese cloth in order to catch any small pieces of scrap or tissue.

—After the lard is lowered into the settling kettle, allow it to stand two to three hours, then siphon to a third kettle, as considerable scrap will have gone through into the lard from the cooking kettle, strain it through a double thickness of cheese cloth stretched over a frame. In the third kettle a scum will arise on it, which should be immediately skimmed off, and about ten pounds of fine salt added to a 5,000-pound batch, to aid in settling. If convenient, it is advisable to allow the lard to settle in this kettle for twelve hours before drawing it off, although this length of time is not necessary, but a perfect settlement of the impurities is necessary to make the best lard.

—After the lard is drawn from the cooking kettle, the scrap should be drawn from the bottom. This scrap is used in the prime steam lard tank. If, however, there is no other provision for handling the scrap, it should be put into a hoop press (Fig. 150), and pressure applied, thereby liberating all the oil left in the residue, the scrap then being used as “pressed scrap.”

—Kettle rendered lard is usually sold and used more extensively during the cooler weather. It is very desirable that there should be a light, fluffy top. This is only possible when the lard is drawn hot in a cool room; chilling the lard rapidly causes this appearance at the top, which is always looked upon by the trade as a mark of excellence. When the lard is drawn off into small packages they are placed one on top of the other, covering the top withpaper. The cover should not be put on the package until it is chilled, otherwise the fluffy appearance is lost.

FIG. 150.—HOOP PRESS.

—When drawn into wooden packages, such as ten, twenty or fifty pound pails, lard should be drawn at 150° F. If drawn into tins it should be drawn off at 175° to 180° F.; when drawn into tierces, barrels or half barrels it should be drawn at about 130° F. When drawing lard into wooden packages they should be silicated the day before, giving them ample time to dry, as this prevents the packages from soaking up the lard and also prevents excessive shrinkage of the package.

—Refined prime steam lard is made into two products, pure refined lard and lard with beef fat added.

—Pure refined lard consists of prime steam lard with lard stearine added. This is a product resulting when prime steam lard is pressed to obtain lard oil, a process described later; however, the quantity available is quite limited. Descriptions will be confined to the making of lard with beef fat added.

FIG. 151.—SECTION THROUGH TANK FOR MIXING FULLERS EARTH AND LARD.

—About thirty years ago the method of refining lard with fullers earth was first inaugurated, and for years only imported earth from England was thought suitable for this purpose. Deposits of fullers earth, of fair quality, have been discovered in the United States and American fullers earth is today used in some lard refineries. Indications are that with improvements in mining and methods of grinding, and possibly also in the discovery of better beds or layers of this substance, manufacturers will not continue to go abroad for supplies of fullers earth.

An explanation of how fullers earth bleaches lard and itskindred fats would be interesting, if anyone knew the exact explanation, but so far there has been no scientific reason given that accounts for this property of this material, therefore no chemical test can be applied to different samples of fullers earth to determine whether they are suitable for refining or not. The only safe test is the practical one of heating a sample together with lard and watching the result of the bleach.

Fullers earth is used for bleaching cotton seed oil and other greases and fats which are subjected to the bleaching process. In improving the color of lard it is done at the expense of flavor, and a wholesome odor, which is natural to the lard, is sacrificed in a greater or lesser degree to the advantage of color. The tendency is to make lard white, even though it loses in odor and taste. In compounding lard this is intensified by the general use of tallow.

FIG. 152.—FULLERS EARTH KETTLE FOR SMALL HOUSES.

—This can be of a predominant size dependent upon the volume of business. For a moderate business the most suitable dimensions are about six feet in diameter and four feet deep. A sectional view of such a kettle is shown inFig. 151and a smaller kettle is illustrated inFig. 152. It was the practice to use compressed air for agitationso as to mix the fullers earth with the lard. This has been discontinued in the best refineries, as it was found that agitation with air had a tendency to make the lard turn rancid more readily than if agitated by mechanical device.

The kettle is supplied with a vertical shaft, to the bottom of which is attached a propellor about fourteen inches in diameter. Around this is fitted a wire screen about thirty inches high made of galvanized wire, ³⁄₁₆-inch mesh, this screen clearing the blades of the fan about an inch. On top of this screen is fixed an iron pipe approaching to within about eighteen inches of the surface of the lard when the kettle is filled. A kettle of this size will hold about 5,000 pounds of lard for treatment. The agitating blade should revolve at a speed of from 125 to 175 revolutions per minute. This has the effect of producing a miniature whirlpool in the body of lard by driving the lard through the screen against the sides of the kettle, where it rises to the surface and goes down through the funnel-shaped tube to be again driven through the screen. In this way the fullers earth is thoroughly mixed in and if there is a tendency to “lump” the lumps are readily broken up by impact.

—If cold lard is used it should be melted and any sediment or moisture which settles should be drawn off. It is best not to draw off too close to the bottom so as to avoid any moisture.

The temperature at which lard should be bleached is an important matter to be determined. If the lard has been heavily cooked and has a strong steam flavor, a temperature of 180° F. is correct. If the lard has not been well cooked a somewhat lower temperature is necessary. As a rule the lower the temperature at which bleaching is done, the more fullers earth is required to get the proper bleach and at the same time as little earth flavor as possible is a point for careful and intelligent consideration. The best way to determine, where there are large quantities of lard, is to take a small sample and make tests in the laboratory. The point to be obtained is to get the bleach with as little of the flavor of the earth as possible. Generally speaking, from three-fourths to one and one-half per cent of fullers earth will get the desired result.

When the lard is brought to the proper temperature, fullers earth is put in the kettle, when it is agitated from eight to twelve minutes, then pumped through the filter press as rapidly as possible. It takes a certain length of time for fullers earth to do its work properly, and a strong agitation of from eight to twelve minutes appears to be the best method to adopt in order to obtain the full effect of the earth.

—Where tallow is used in lard, it is always advisable to bleach the tallow separately. This is done in the same manner as described for lard, with the exception that about three per cent of fullers earth is used, after which it is pumped through the filter press and into the receiving tanks.

FIG. 153.—FILTER PRESS.

When it is compounded with the lard, the desired amount should be put into the kettle with the lard after it is treated. The same is true of oleo-stearine, except that in the bleaching of this article from one-half to one and one-half per cent of fuller earth is sufficient. Measures must be taken to see that ingredients are intimately mixed before passing the product to the rolls.

The use of tallow or stearine is for the purpose of cheapening the product, as well as hardening it, the formula for same being made according to the values and conditions under which the lard is to be sold. For instance lard going south, or into a warm climate, is made much harder than lard for a temperate climate; hence lard formulas, generally speaking, are worthless for general use, the different formulas being made to suit widely different conditions, and their availabilityalso depends to a considerable extent upon the fluctuation of values.

—After the contents of the kettle have been pumped through the filter air pressure should be turned into the filter press in order to blow out all the lard possible. After this live steam should be turned on, expelling the balance of the lard from the pipe. A large portion of this latter lard, however, is unfit to be used again, as it contains sediment and fullers earth combined, having a rank, strong odor, and can be used only for grease.

FIG. 154.—LARD COOLING CYLINDER.

—This is a device provided for cooling lard in a film so as to bring plenty of air in contact with the surface during the congealing. After the lard has been put through the filtering press it goes to a receiving tank and is next passed over rollers for chilling. (Fig. 154.) These are cast iron cylinders containing refrigerated brine. The cylinders revolve at from ten to fourteen revolutions per minute, the lard being congealed on the outer surface. Fixed against the side of the cylinder is the edge of a steel knife which scrapes close to its surface. The lard, in contact with the cool surface of the cylinders, congeals and as it passes to the knife it is removed and drops into the trough. Here it is thoroughly beaten by a revolving shaft with pickers on it, so that all lumps are broken and the grain is of a smooth, even consistency. Pure lard passes to an agitator, which is a jacketed kettle, whereit is given a thorough agitation and drawn off cool as possible, the object being to have the different ingredients thoroughly mixed at a low temperature.

At times rolls are used in tandem. When a bountiful supply of cold water, say at 60° F., is available, the saving in refrigeration justifies the use of tandem rolls. In this instance the first roll is elevated so as to gravitate the lard to the feed of the second.

WEIGHT OF LARD PACKAGES.

—Refined lard is not usually drawn in a cooler. In most climates the non-refrigerated rooms will suffice. It is packed in tubs, barrels or tierces of wood. The lard, when available, in the picker trough, is usually chilled and stiff. The use of a pump is made to withdraw and force it through a strainer in an enlarged section of the pipe, so as to effectually break all lumps. A relief valve should be placed on the line to spill into the picker in case the draw cocks are all suddenly closed.

—In wooden packages tare is deducted. The table on preceding page shows the actual weight of the different packages which are usually made from an X L grade of tin. Inasmuch as lard sells at more per pound than the tin costs, there is always an endeavor to get the packages as heavy as consistent.

—Many moderate sized plants that do not cater to a trade accustomed to highly refined lard, prefer to make kettle rendered lard as most of their output, using leaf, back fat and trimmings, adding the complimentary proportion of killing lard and agitating the whole in a water jacketed agitator. All implements used are similar to those described previously, also the method of drawing from the agitator to packages is the same. Beef fat can be rendered in the same way when oleo departments are not operated, and it can thus be used to good advantage.

—Compound is a substitute for lard and is made of cotton seed oil and oleo stearine, or tallow, or both. The formula on this article varies according to the relative values of the ingredients. The generally accepted formula is 80 per cent cotton seed oil, and 20 per cent oleo stearine.

If the market price of oleo stearine is high, a formula may be substituted as follows: 75 per cent cotton seed oil, 7¹⁄₂ percent tallow, 17¹⁄₂ per cent oleo stearine. In cold weather even a smaller amount of stearine may be used and a proportionately larger amount of tallow.

—This is a product derived from cotton seed. Before the manufacture of cotton seed oil, the cotton seed, removed from the cotton, was thrown in large compostheaps and after decomposition, was used sparingly as a fertilizer. An idea of its value may be gained from the following table. From one ton of seed, by average, is obtained:

The oil when extracted from the seed is termed “crude oil.” In refining this oil the loss varies from 7 per cent to 12 per cent, on an average about 9¹⁄₄ per cent.

—The crude oil is purchased by refiners and treated to produce “yellow oil.” In this process it is put into a tank (it is generally considered profitable to refine cotton seed oil only in large quantities) supplied with a revolving agitator. Into the tank is put a solution of eighteen to twenty per cent caustic soda. The quantity and strength of the solution necessary is determined by treating a small sample. To a small sample of oil add the soda solution, stirring continuously, having it heated to a temperature of 160° to 180° F. When sufficient soda lye has been added a floculent precipitation will be noticed. This indicates a “breaking” of the oil. By calculation of the relative amount the comparative quantities can be arrived at.

An excessive amount of lye will saponify its equivalent in good oil, therefore care must be exercised to see that only the proper amount is used. In a practical way the soda is introduced in the crude oil solution and agitation is started to insure the thorough mixing of the caustic soda and the oil. The floculent substance appearing, the agitation is stopped and the oil allowed to settle, the sediment and substance other than oil collecting at the bottom of the tank. A small quantity (about one-quarter of one per cent by weight) of fullers earth is added and the oil removed by pumping through a filter press producing what is known to the trade as “yellow oil.”

The sediment, known as “foots” is collected in kettles and treated with additional lye, boiled and settled with salt; water added, settled and drawn. This treatment is duplicated asmany times as necessary, until the soap stock will separate from impurities. When thoroughly settled draw the soap stock into packages for the soap trade. The finished “foots” contains about 33 to 40 per cent of moisture and a small percentage of lye.

—The “yellow oil” of trade has a decided flavor which it is desirable to remove, and this process is accomplished by deodorizing. (SeeFig. 155.)

—This tank is equipped for heating the oil to a very high temperature by the introduction of a large coil surface, preferably rings, one within the other and arranged so that each ring is accessible. The kettle coils, etc., should be made extra heavy. The top of the kettle must also be hooded and as the oil boils violently the steam must be given free opportunity to escape. The escape pipe should be at least sixteen to twenty inches in diameter in a tank six feet in diameter, and should be provided with a goose neck, so that the steam rising which condenses, does not drip back into the tank.Fig. 155show the construction of an oil treating tank.

The exhaust pipe extends into the atmosphere a short distance above the deodorizing tanks. On account of the extreme agitation caused by the heat, the oil is likely to boil over and waste. Special attention is called to the crook or neck in the exhaust pipe with two-inch outlet at the lowest point. This is done so that the condensation will not run back into the oil, but can be taken out at this point.

—The tank is filled with oil to about half its capacity. The oil is then heated to a temperature of 320° to 360° F. After being held at this temperature for an hour to an hour and a half, it is ready for the washing process. This is done by means of a two-inch perforated pipe at the top of the kettle, through which is sprinkled cold water on the oil. The extreme temperature evaporates the water very rapidly and at the same time causes a precipitation. The water should be allowed to run for five minutes, and then the body of oil should stand for from one to two hours. The cone, or bottom of the kettle, will be found to have a sediment which has been precipitated from the oil. This “bottom” should be drawn off, and the steam again turned on the coils.

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