The importance of milk is hardly greater than that of its two chief products, butter and cheese. Butter consists chiefly of the fat of the milk with a small amount of water, of casein and of salt, with sometimes a little milk sugar. The average amount of fat contained is 82 per cent. The fats which are present may be put into two classes: Those derived from the so-called "fixed" fatty acids, and those from the volatile fatty acids. The fixed fatty acids are present in the form of stearin, the chief ingredient in beef fat, and of palmitin and olein. The amount of the volatile acids present differentiate butter from most of the other fats that we commonly use as food. The flavor of butter is produced apparently by the action of bacteria upon the cream, the different flavor of butter at different times of the year coming largely from differences in the kind and amount of bacteria that find their way into the milk. The "ripening1' of the cream is often induced by artificial cultures of the proper bacteria. Many buttermakers abroad and in some sections of our own country, depend entirely upon these bacterial cultures for the production of their butter flavor.
The rancidity of butter may be produced by changes taking place in the casein that is present, or from a decomposition of the fats themselves. Cooking lessens the digestibility of butter as it does that of other fats, probably because of the decomposition that takes place when fats are subjected to a high temperature, and the consequent freeing of irritating fatty acids.
The adulteration of butter consists chiefly in a substitution of other substances, either in whole or in part, for the butter fat, or of an inferior and "doctored" article. The coloring of butter is almost universal, but it is so generally accepted that it can hardly be classed as an adulteration, although it surely shows a false standard in foods when we insist upon buying a deep yellow compound colored with annatto or some other foreign material instead of the delicate straw-colored substance that most natural uncolored butter is.
The substitutions spoken of are chiefly either what is called renovated butter, or oleomargarine. Renovated butter is made by taking different lots of stale or rancid butter, melting it, allowing the curd to settle, and re-churning the fat with a small amount of milk. The product is certainly better than the rancid butter, but it cannot compare in flavor and in wholesomeness with fresh butter, and certainly should not be sold as such.
Oleomargarine, or butterine, is made by clarifying the fat of beef and churning it in milk. It differs from butter in its composition in that it contains practically no curd, and is lacking in the volatile fatty acids that are present in the butter and characteristic of it. It is a cheaper product than butter, and the temptation to put it upon the market under the name of butter has consequently been great. There is absolutely no reason, however, why, sold under its own name, it should not be a very general article of use. There seems nothing to show that it is materially less digestible than butter itself; it does not grow rancid with the ease that butter does, and it is made in a perfectly cleanly and wholesome way, certainly so far as the best quality of it is concerned. Even if it is artificially colored, this is no worse than is true of butter. The difference in taste between it and butter is rather in an absence of the aroma that we find in the best butter, than in any disagreeable flavor present. Indeed, although each person thinks to the contrary in regard to himself, few people are able to distinguish it from butter by taste. It may be used in almost every way as a butter substitute. It is perfectly satisfactory to use in the making of sauces or upon vegetables or meat. It does not make so light a cake as butter, and is not satisfactory for this purpose, except that in a plain cake it may be substituted for part of the butter; and it cannot be used in candy making as, for some reason, it fails to combine with the other materials and always separates out upon cooling. Since it is so much cheaper than butter it would be well to use it as a substitute for part of the more expensive material.
The present law in regard to it has lessened its sale to a great extent since it can no longer be artificially colored, but it is certainly only prejudice that prevents our accepting a pure white fat instead of a bright yellow one.