210 



CHEMISTRY OF FARM PRACTICE 



TABLE XXIII. COMPOSITION OF CREAMERY BUTTERS. 



(WISCONSIN EXPERIMENT STATION) 



Good butter should contain at least 80 per cent fat and, 

 preferably, it should run 83 per cent fat. Genuine butter 

 may usually be distinguished from oleomargarine without 

 any special test. Most oleomargarine is more solid than 

 butter and is brittle and hard when cold. When soft, it is 

 smeary and shows no grain. 



Process butter is manufactured from old or poor butter. 

 It is first melted and treated with steam to carry off any of 

 the disagreeable acids which have resulted from the decom- 

 position of the fat. It is then mixed with milk, solidified, 

 salted and worked. Process butter has properties similar 

 to those of oleomargarine. 



A simple test for butter is to heat it to boiling, carefully, 

 in a tablespoon. Good butter boils with little noise and 

 spatter and produces an abundance of foam. Oleomar- 

 garine and process butter boil with considerable spattering 

 and produce little foam. The " meaty " odor when hot 

 is characteristic of the animal fats used in oleomargarine. 



157. Cheese. Cheese is made by coagulating milk 

 when heated. American cheddar- cheese is made by heating 

 the milk to 80 Fahrenheit and adding a small amouut of 

 rennet extract. The casein in the milk is coagulated by 

 the rennet and holds the fat. The green cheese analyzes 

 about 37 per cent water, 34 per cent fat, 24 per cent pro- 

 teids, the other 5 per cent consisting of mineral salts, lactic 

 acid, and milk sugar. Most of the milk sugar and albumin 

 is drawn off in the whey. 



