Adulteration of Lard.—The principal adulteration to which lard is subjected is admixture with other and cheaper fats. Among the fats which are used for this purpose may be mentioned beef fat and cottonseed oil. Beef fat has a higher melting point than lard and cottonseed oil a much lower melting point, being liquid at ordinary temperatures. A mixture of beef fat and cottonseed oil may, therefore, be made, having approximately the same melting point as lard itself. The addition of this mixture to lard would not alter its melting point to any sensible extent. Instead of using the whole cottonseed oil for the purpose mentioned it may be previously chilled and its product of a higher melting point, or as it is sometimes called, the stearin of cottonseed oil, may be used for admixture with lard. Large quantities of these mixed fats were formerly made in this country under the name of "compound lard" in which the above adulterants were the chief constituents. The laws of the various states are happily of a character which forbids the sale of a mixture of a compound of lard and other fats under the name of lard, although there is no objection to such admixture from a hygienic and dietetic point of view. There are many hygienists who are of the opinion that the more extended use of vegetable oils instead of lard would be of value to the health of the public. If this be true, the admixture of a vegetable oil with lard would improve it from a hygienic standpoint. The principal, perhaps the sole, objection to such admixtures is their fraudulent character. Vegetable oils, especially cottonseed oil, being very much cheaper than lard, their use in lard without notification cheapens the product and defrauds the customer. Lard may also be adulterated with its own stearin. In the manufacture of lard oil a residue is left of a much higher melting point and this residue may be mixed with a vegetable oil, such as cottonseed, in the production of a compound of approximately the same melting point as lard itself. In a case of this kind both constituents are fraudulent, in as much as neither the cottonseed oil nor the lard stearin may be regarded in any sense as lard.
Detection of Adulterations.—The presence of cottonseed oil in any form in lard is at once determined by the application of a simple color test known as the Halphen test. This is not a reliable test in those cases where the animal has been fed cottonseed.
Halphen Reaction for Cottonseed Oil.—Carbon disulfid, containing about one percent of sulfur in solution, is mixed with an equal volume of amyl alcohol. Mix equal volumes of this reagent and the oil under examination and heat in a bath of boiling brine for fifteen minutes. In the presence of as little as one percent of cottonseed oil an orange or red color is produced, which is characteristic.
Lard and lard oil from animals fed on cottonseed meal will give a faint reaction; also the fatty acids thereof.
This test is more sensitive than the Bechi test (nitrate of silver) and less liable to give unsatisfactory results in the hands of an inexperienced person.
