MILK PRODUCTS 



325 



The composition of butter milk apart from the amount of 

 fat in it is similar to that of skim milk. The lactic acid 

 formed during the process of ripening may amount to about 

 o'8 per cent, of the butter milk, and the percentage of milk 

 sugar is correspondingly diminished. 



The various products obtained in butter making are sub- 

 ject to variations from the causes above mentioned. Some 

 idea of their average composition may, however, be formed 

 from the following analyses. The relative quantities of the 

 products, and the actual quantity of fat in each are also given. 



It appears, therefore, that about 90 per cent, of the fat in 

 the 'original milk may be recovered as butter, and about 

 TO per cent, is lost in the skim and butter milk. The loss of 

 fat may be diminished by using the mechanical separator; 

 when the older methods of skimming are employed it is often 

 much greater. 



Butter. According to the above estimate, rather more 

 than i Ib. of butter should be produced from each pound of fat 

 in the original milk. In other words, the total amount of 

 water, curd, and salt in the butter just exceeds the total loss 

 of fat. As butter consists essentially of fat it is not subject to 

 very great variation in composition. The variable constituents 

 are, of course, the water and salt. In this country the amount 

 of water in butter is limited by law to 16 per cent.; any 

 excess over that amount is regarded as fraudulent addition. 

 Salt is added to butter for the double purpose of preserving it 



