The Method Used for Refining Lard in Large Packing Houses. — (Copyrighted; Reprint Forbidden.)
The large packers all refine Lard and Tallow with the Fuller’s Earth process, and for the benefit of the small packers, who would like to know how it is done, we will give the full directions, although a small packing house can hardly afford to put in a plant for the process, as it requires a man who is experienced to refine Lard and Tallow in this manner. If a packing house does not make enough Lard and Tallow to afford to keep a man especially for this purpose, it will not pay to put in a refinery, which consists of the following machinery: A Receiving Kettle, which is a large open tank with steam coils in it to dry the Lard or a large Jacket Kettle will do. A Clay Kettle, which is a tank with steam coils in it for heating the Lard and an air pipe at the bottom of it connected to an air compressor. A Lard Cooler with Agitator to cool and stir the Lard while it sets so as to have it thoroughly mixed. A Pump, Air Compressor and Filter Press. An ordinary size outfit will cost from $2,000 to $3,000.
First, the Lard, Tallow or Cotton Seed Oil, which is termed stock, is placed in the Clay Kettle. The Clay Kettle is simply an iron jacket with a coil in the bottom of it through which air is pumped. In this kettle, the Fuller’s Earth is added. To each and every 100 lbs. of stock, there is added from one to two lbs. of Fuller’s Earth; the quantity depending upon the grade of stock. Before the stock is treated a small test is made as follows. A small quantity is heated; in a part of it one per cent of clay is put, in another part 1½ per cent, and in another two per cent. Mix each lot thoroughly, put them into a funnel over filter paper and allow them to filter. By examining these samples, one can tell how much earth to use to the stock in the kettle. This must be done when the stock varies. Of course, when the Lard, Tallow, or Oil are running uniform, it is not necessary to make the test, but where the stock changes, it is always advisable to test before treating, for the reason that too much Fuller’s Earth put into the stock will give the Lard an objectionable flavor. Before stock of any kind can be treated with Fuller’s Earth, all the moisture must be out of it; Lard usually contains two to three per cent of moisture, and very often considerably more, so it must be heated in a Jacket Kettle until all the water is evaporated. If there is any water in the Lard, the Fuller’s Earth attacks the water first, and the Lard is not affected, because wet Fuller’s Earth has absolutely no effect upon Lard. When the Fuller’s Earth is added to Lard, it must be 155 degrees hot; Tallow must be 185 degrees hot, and Cotton Seed Oil 140 degrees hot. After the desired heat is obtained, regulate the steam so the temperature will remain stationary, turn on the air, and when it is blowing hard, put in the Fuller’s Earth and blow for about 20 minutes; then start the force pump and pump the stock through the Filter Press. If the stock is of fine quality and only a small percentage of Fuller’s Earth is used, it can be pumped directly into the Receiving Kettle, but if a large percentage of Fuller’s Earth is used, it is advisable to let the Lard run back into the Clay Kettle, and keep on letting it run through the filter and pumping it round until it is thoroughly clarified; then allow it to run into the Receiving Kettle.
If inferior stock is used, sometimes as much as four and five per cent of Fuller’s Earth is used to refine it, but it is not advisable to use that large amount as the clay gives off an odor which the stock sometimes absorbs. Always use the least amount of clay that good judgment indicates will do the work, and after pumping through the filter, if it is not as it should be add more clay and refilter it.
To make Compound Lard, treat the different stocks separately, run them in different tanks, and then mix them. After they have been put into the receiving tank or the mixing tank, it is advisable to mix them by blowing air into the bottom of the kettle in which are Lard, Tallow and Oil; this will mix even better than any process or method that we know of. The amount or kind of stock to be used depends upon the season of the year, and the kind and quantity of goods you wish to make. Equal parts of Tallow, Lard and Oil make a very good Compound. All the cloths for the Filter Press should be washed every day after using them as they must be kept perfectly clean; the cleaner the better.
After the Compound Lard has been thoroughly mixed it must be put into an Agitator and agitated until it is thick like cream before it is run off into buckets.