In case of lard, killing and cutting lard should be intimately mixed in equal proportions if possible.
Titer in Tallow and Lard.
—Titer in tallow, frequently referred to, is a relative test of hardness. The test was originally devised for the use of candle makers who wanted an oil containing the largest percentage of stearic acid. Stearic acid has a hardness of about 55° Centigrade. The hardness of other substances is relative to this as follows: commercial oleo stearine, about 50.5° C.; tallow, 41° to 43° C.; No. 2 tallow or grease, 39° to 43° C.; P. S. lard, 35.5° to 37° C. Every trimming in the animal has a different hardness; the thinner the cattle, the harder the tallow. Bone fat or marrow is very soft. Animals of different feeding show varying hardness, so there is no method of manufacture that will vary the hardness content of product other than selection. In a general way, cattle ruffle, caul, or that used usually in oleo melting is relatively hard. For example, oleo stock will analyze as hard as 46° C., while the tallow from the same house will analyze 43° C.
This hardness is determined in the chemical laboratory as follows: The fat is melted and 25 cubic centimeters are drawn and mixed with 20 C. C. wood alcohol, 10 C. C. of 50° Baume caustic soda solution and the contents boiled until completely saponified. The alcohol is evaporated by drying. The residue is ground and boiled with an excess of diluted sulphuric acid until all the soap has been changed to fatty acid and the clear oil floats. The water in the vessel is drawn from below the fat, and the fatty acids collected in a glass vessel, which are allowed to stand on steam coils until the oily stratum is clearly defined. The fatty acids are placed in an observation room and the point of solidification observed. The result is the titer, which is the degree Centigrade at which the fatty acid from an oil or stearine solidifies after being melted.
The other item of consequence in tallow analysis is the rancidity, known as the free fatty acid. This should be kept low and is usually variable with the care given the product. No. 1 tallow, for example, should show under two per cent of low grade greases, and will run as high as twenty per cent.
Steam for Cooking.
—A question frequently asked is the quantity of steam required to cook a tank. An accurate test conducted on a mixed tank of pork products, killing and cutting stock, under standard conditions showed thus:
| Weight of Raw Stock | 12,266 | ||
| Water filled in Tank | 9,634 | ||
| 21,900 | |||
| After Cooking:— | |||
| Lard | 6,040 | ||
| Skimmings | 479 | ||
| Water Tankage | 19,360 | ||
| 25,879 | |||
| Accumulation-Steam Condensed | 3,979 | ||
| Steam per 1,000 pounds, Raw Stock | 324 | lbs. | |
Cooking Test and Expense.
—The following test on the cost for cooking was made on killing and cutting lard—very large digesters—and from it valuable deductions can be made. Expert opinion has pronounced test No. 1 and test No. 3 as producing comparatively the best results in manufacture.