140 SCIENCE AND PRACTICE OF CHEESE-MAKING 



cheese-making process and passes out, for the most 

 part, with the whey. Numerous attempts have been 

 made to recover in cheese all or most of the albumin 

 present in milk, but we know of no case which has 

 resulted in making a product like normal cheddar 

 cheese in its properties. 



MILK-FAT 



Milk-fat, also known as butter-fat, is not a single 

 chemical compound, but is a somewhat variable 

 mixture of several different compounds called 

 glycerids. Each glycerid is formed by the chemical 

 union of glycerin as a base with some organic acid 

 or acids of a particular kind (butyric, palmitic, 

 oleic, etc.). Under the action of certain kinds of 

 micro-organisms, milk-fat undergoes decomposi- 

 tion, forming among other products free butyric acid, 

 which is the compound responsible for the offensive 

 flavor of rancid cheese and butter. 



Fat-globules in milk. Milk-fat is present in milk, 

 not in solution, but suspended in the form of very 

 small, transparent globules. The globules vary in 

 size, the smaller being more numerous than the 

 larger ones. The average size of fat-globules in 

 milk is somewhat larger than one ten-thousandth 

 of an inch in diameter. Contrary to what has been 

 formerly taught, the fat-globules of milk have no 

 special kind of covering, but are simply minute 

 particles of fat, floating free in milk in the form of 

 an emulsion. Skim-milk and whey contain few 

 globules, as compared with normal milk, while 

 cream, of course, contains many more than normal 



