22 Testing Milk and Its Products. 



27. In the manufacture of American clieddar cheese, 

 whole milk is heated to about 86 F., and a small 

 amount of rennet extract is added, which coagulates the 

 casein; the albumen of the milk is not precipitated by 

 rennet and remains in solution (18). " Green" cheese, 

 as taken from the press, is made up, roughly speaking, 

 of 37 per ct. of water, 34 per ct. of fat, 24 per ct, of 

 albuminoids (nearly all casein), and about 5 per ct. of 

 milk sugar, lactic acid, and ash. In the curing of cheese 

 there is some drying off, but the main changes occur in 

 the breaking up of the firm curd into soluble and digest- 

 ible nitrogenous compounds, peptons, amids, etc. 



Whey is the by-product obtained in the manufacture 

 of cheese. It consists of water and less than 7 per ct. ol 

 solids; of the latter about 5 per ct. is milk sugar, .8 per 

 ct. albumen, .6 per ct. ash, and .3 per ct. fat. Whey is 

 generally used for feeding farm animals; it is the raw- 

 product from which milk sugar and whey cheese are made. 



28. Condensed milk is manufactured from whole milk 

 or from partially skimmed milk. In many brands a large 

 quantity of sugar (33 per ct. or more) is added to the 

 condensed milk in the process of manufacture so as to 

 secure perfect keeping quality in the product. Other 

 brands to which no sugar has been added are, however, 

 on the market, and in case of such brands the relation 

 between the various solid constituents of the condensed 

 milk will be essentially the same as that between the 

 constituents of milk solids. Condensed milk should con- 

 tain at least 10 per ct. of fat, and must be free from pre- 

 servatives and all other foreign substances (except sugar). 



Tables are given in the Appendix showing the average 

 composition of the various milk products. 



