Composition, nutritive value and cost of milk

or nearly all the fat is removed there is still an opaqueness left, which is probably due to one of the mineral salts, phosphate of lime, which exists only in small quantities.In considering a subject like this we dwell upon one that interests all, for the milk produce in x889 was estimated to be worth not less than $37u,uou,uuu, estimating in the aver age that each person in the U. S. consumed annually 25.5 gallons of milk.The exact extent of the dairy industry is not known but according to Farmers Bulletin No. 42 it is safe to say that it exceeds any other branch of industry.Now that we have seen what milk is, let us learn a few facts about it.The curdling of milk is generally due to the action of acids upon the casein.The casein is that part of the milk which is employed in cheese making.The curd produced in cheese making is due not to the acid but to the action of rennet, an unorganized ferment found in the stomach of the calf.The curd produced by acid is generally dissolved by the addition of alkalies, but that produce by rennet is unaffected.By dissolving the curd it is sometimes made possible to get a partial analysis of milk which could otherwise not be tested, ihe natural curdling or souring of milk is due to the lactic acid which is found in the milk as a result of the decomposition of the milk sugar, through the action of S B bacteria.Every body that has used milk to any extent has seen a scjim on the milk after boiling.This is due to the heat -3coagulating the protein of the milk, the greater part of which is albumen although casein may enter into it to some extent.It will be seen from the following data that the vari ation in the chemical composition is great.Milk probably varies in composition and nutritive value more than any other food product.Not only does milk vary greatly in its chemical compo sition but it is a well known fact that milk is an excellent medium for the growth and development of bacteria.Although the bacteria do not affect the chemical composition, or at most only to a slight extent, or probably change the nutritive value of milk, they do endanger the health of the consumer.For this reason the milk supply of our cities should be carefully and thoroughly examined and tested.All the females of the mammalian group support their young for a shorter or longer time upon their own milk.The composition of these milks varies greatly as can be seen from the analysis of Konig, who analysed milk from about a dozen different species of this group.But these milks will not be considered in this paper for they are seldom if ever sold on the markets for food.Although a few are used on rare occasions they are never extensively used.Chemical analysis is the only accurate way to deter mine the composition, and in part the nutritive value, and cost of milk.A number of methods have been proposed for deter mining the content of fat in milk.Fat, however, is not the