MILK, BLOOD AND URINE 217 



Composition of Butter 



Fat 84.0 per cent 



Water 12.73 per cent 



Protein 1.30 per cent 



Ash and Salt 1.97 per cent 



The different substitutes for butter are of two types. Reno- 

 vated or Process Butter consists of old rancid butter worked over 

 to remove objectionable substances and to incorporate a small 

 amount of fresh milk or cream. Oleomargarine j Butter ine and 

 similar products consist of mixtures of animal fats, other than 

 milk fat, such as beef fat and lard, to which also some fresh 

 milk or cream is usually added. 



Cheese 



Cheese consists principally of the coagulated casein of milk 

 separated by natural souring of the milk or by the use of com- 

 mercial enzyme preparations known as rennet (rennin). The 

 curd carries down with it most of the fat and some of the other 

 constituents of the milk. After separation the curd is worked 

 into various forms of cheese, and most varieties, except the 

 soft fresh cream cheeses, are subjected to a fermentation or 

 ripening. The fermentation produces various substances 

 which give to the cheese a particular character and flavor. 

 The average composition of Cheddar cheese made in New York 

 State may be given as follows, according to Van Slyke : 



Composition of New York Cheddar Cheese 



Water 32.7-43.9 per cent 



Fats 30.0-36.8 per cent 



Proteins 20.8-26.1 per cent 



(Milk sugar, lactic acid, ash and salt about 5.0 per cent.) 



Whey. — The filtrate obtained when the coagulated casein 

 is separated is known as whey. It contains the soluble pro- 

 teins, practically all of the milk sugar, and some of the inorganic 



