fat. Margarine is the legalized and therefore legitimate butter-surrogate, prepared by churning any suitable fat with milk into a cream, solidifying the latter by injection into cold water and working the lumps together, precisely as is done in the case of the churned cream of milk. The substitution of margarine for butter is frequent, in spite of all legal enactments directed against this fraud, the semblance between butter and margarine being so great that a trained palate is necessary to distinguish the two articles. Much more frequent and much more difficult to deal with is the sale of mixtures of butter and of margarine. In order to show the difficulties inherent to this subject, it will be necessary to consider the chemical nature of butter-fat, and to compare it with other fats that may enter into the composition of margarine. Butter-fat is butter freed from water, curd and salt and extraneous matter. Like the greater number of natural fats it consists of a mixture of triglycerides, that is, combinations of glycerin with substances of the nature of acids. These acids, in the case of fats other than butter-fat, are mainly oleic, palmitic and stearic acids. Butter-fat, in addition to these, contains other acids which sharply distinguish it from the vast majority of other fats and, with the exception of cocoa-nut oil, from those substances which are or may be used to mix with butter, by the circumstance that a considerable proportion of its acids, when separated by chemical means from the glycerin, are readily soluble in water, or may be easily volatilized either alone or in a current of steam, whereas the acids separated from the foreign fats are practically both insoluble and non-volatile. This fundamental principle serves at once to distinguish, for example, between butter and margarine, and has been made use of by analysts not only for this purpose but also with a view to determine the relative amounts of butter and margarine in a mixture of these substances. Thus butter-fat contains about 88%, more or less, of “insoluble fatty acids,” while margarine contains about 95·5%; 5 grammes of butter-fat when chemically decomposed yield an amount of volatile fatty acids which requires about 26 cubic centimetres (more or less) of deci-normal alkali solution for neutralization, while margarine requires mostly less than 1 cubic centimetre (Wollny or Reichert-Meissl method). There are other differences between the two kinds of fat: the specific gravity of butter-fat is higher than that of most other fats; its power of refracting a ray of light is less; the “iodine absorption” of butter-fat is smaller than that of many other fatty matters, and so on. But the composition of perfectly genuine butter-fat varies within somewhat wide limits. The milk from a cow fed on good and ample food in warm weather yields a fat that is rich in characteristic butter-constituents, while a poorly fed animal, kept in the open till late in the autumn, when the nights are cold, gives milk exceptionally poor in fat, the differences expressed as “insoluble fatty acids” lying between 86 and 91%, and in volatile acids, expressed as “Wollny” numbers, between 18 and 36. Generally, therefore, summer butter is rich and autumn butter poor in volatile acids, or, geographically, Australian butter is more frequently high, Siberian often exceedingly low in these acids. The food of the animal also may, under certain conditions, yield a notable proportion of its fatty matter to the butter; cows that have, for instance, been fed upon large quantities of cotton-seed cake yield butter in which the cotton-seed oil may be traced, and the same holds good with other fatty foods. All these, and other circumstances, combine to render the detection of small quantities of foreign fats that have been fraudulently added to butter almost a matter of impossibility. This is perfectly well known to unscrupulous butter dealers, and an enormous amount of adulteration is known to be practised. Even small amounts of adulteration could, nevertheless, often be discovered while margarine manufacturers employed considerable proportions of vegetable oils in their products, some of these oils furnishing characteristic chemical reactions allowing of their discovery. Here some firms of margarine manufacturers came to the aid of the butter-mixer and produced margarine containing nothing but animal fat, so-called “neutral” margarine being freely offered for fraudulent purposes. There is one fat besides butter which contains “volatile fatty acids,” namely, cocoa-nut oil. Since means have been found to deprive this fat of its strong cocoa-nut odour and taste, it has largely been used in the adulteration of butter, and margarine containing cocoa-nut oil and other fatty substances has freely been manufactured and sold specially for butter adulteration. The seat of this class of fraud is mainly in Holland. Analysts happily found means to detect this oil when present above 10%, and numerous prosecutions made mixers more careful. Abundant evidence, however, exists showing that the simultaneous addition of water or milk so as to keep the water limit below 16% and that of margarine entirely composed of animal fats below 10% leaves a large margin of profit with a very small chance of detection. For the moment at least analysis has had the worst of it in the battle between honesty and “business methods.”
Margarine itself is a legitimate article of commerce (when sold with due notice to the purchaser), but is frequently adulterated. As regards the fats used in its manufacture there does not exist any legal restriction, and as long as the fat is in a state fit for human consumption the manufacturer can make whatever mixture he pleases. In general there is no reason to think that any bad or disgusting fats are finding their way into the factories, which in most countries are under proper supervision; the old stories about recovered grease from all sorts of offal are quite without foundation. But a considerable percentage of solid paraffin has been met with as an admixture of the fatty part of margarine. As the fatty portion of the article is the only one of value, some manufacturers make great efforts to produce margarine with as small a percentage of fatty matter as possible, either by incorporating excessive amounts of water or of milk—margarines with over 30% of water being met with—or by introducing sugar, glucose, starch, gelatinous matter, in fact anything that is cheaper than fat. The English law imposes a limitation upon the percentage of butter-fat that may be contained in margarine, but at present at least the tendency of manufacturers is all for having as little butter or other valuable fat in margarine as is practicable, and not to err on the other side. For the purpose of facilitating the discovery of margarine when it has been fraudulently added to butter, some countries (Germany, Belgium, Sweden) insist upon the use of from 5 to 10% of sesame oil (from the seed of Sesamum orientale or S. indicum, belonging to the family of Bignoniaceae) in the manufacture of such margarine as is to be consumed within the countries in question. This oil yields a characteristic red colour when it, or any mixture containing it, is shaken with an hydrochloric solution of either sugar or furfurol, and is intended to serve as an “ear-marking” substance. The addition of a little starch or arrowroot, easily discoverable chemically or by the microscope, is also required by Belgium, but in the absence of any international agreement these ear-marking additions are of little practical use. It is, however, interesting to point out that, while complying with the regulations of the governments, margarine manufacturers of the countries named have found an easy way of rendering the regulations quite nugatory: they add methyl-orange, a colouring matter which itself produces a red colour with acid and quite obscures the real colour obtained by the official test for sesame oil.
Cheese may be legitimately made from full-milk, milk that has been enriched by addition of cream, or from milk that has been more or less skimmed. It varies consequently very widely in composition, so-called cream cheese containing not less than 60% of fat; Stilton upwards of 40%; Cheddar about 30%; Dutch, Parmesan and some Swiss and Danish less than 20%. The amount of water varies with the kind and age of the cheese and may be as low as 20 and as high as 60%. Under these circumstances it is impracticable to lay down any hard-and-fast rules as to the composition of cheese. When, however, cheese is made from skimmed milk and the fat is replaced by margarine, as is the case in so-called “filled” or margarine cheeses, the sale of these amounts to an adulteration, unless the presence of the foreign substance is declared. It may at first sight appear strange that the person who robs milk of its most valuable
