How the adulteration of butter is done with substituents?
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 substitutions used as adulterants are chiefly either 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 cheaper than butter and sold to the customers in the name of original butter. It is materially less digestible than butter itself; it does not grow rancid with the ease that butter does.