THE COMPOSITION OF BUTTER 357 



is due to the overrun, and that by overrun is meant the increase 

 in quantity of butter over butter fat secured by churning. The 

 butter fat paid for at the creamery is the clear oil. Butter is not 

 all oil, but contains water, salt and curd also. The analysis of 

 100 pounds of ordinary butter shows a composition about as 

 follows : 



Per Cent 



Water 14 



Salt • 2% 



Curd 1 



171/2 

 Fat 82% 



100 



In other words, 82.5 pounds of fat, by the addition of water, salt, 

 and curd, has been made to become 100 pounds of butter. 



Viewing the same matter slightly differently we may figu 



re 



that 100 pounds of fat taking up 19 pounds of water, 3.5 pounds 

 of salt, and 1 pound of curd, will produce 123.5 pounds of butter. 



In good home dairy practice the test of the cream may be 

 ascertained with a fair degree of accuracy by churning it, weigh- 

 ing the butter, and subtracting from the weight of the butter, 

 one-sixth its weight, and then dividing the remaining five-sixths 

 weight by the number of pounds of cream used at the start. This 

 method of checking should show an agreement within 2 per 

 cent of fat with that allowed at the creamery. 



Under skillful method of manufacture the quantity of butter 

 over fat may be as high as 22 per cent without the incorporation 

 of such a quantity of water or salt as to render the butter either 

 inferior or illegal. And if the overrun falls as low as about 16 

 per cent regularly, something is wrong. The cream may be 

 inaccurately sampled or tested, the fat loss in the buttermilk may 

 be excessive or some other leak is present. Buttermilk should 

 not test more than 0.05 or 0.09 per cent fat. 



The composition of butter varies somewhat with the 

 methods and temperatures used in making. Butter may easily 



