STANDARDIZATION OF MILK AND CREAM 1 17 



In the above example we would have 3.2 -h 4 = 0.80. 

 Hence 80 per cent of 4-per-cent milk and (100 — 80 = 20) 

 20 per cent of skim milk will produce milk containing 3.2 

 per cent of fat. 



I. (b) To obtain 100 pounds of milk containing 3.2 per 

 cent of fat from milk containing 4 per cent of fat, and skim 

 milk. 



Determine the number of pounds of fat required. Divide 

 this number by the per cent of fat in the known milk. This 

 will gi^-e the pounds of known milk required. 



100 X S-- per cent = 3.2 which is the pounds of fat in 

 100 pounds of 3.2 per cent milk. 



3.2 -H 4 = 0.80 or 80 per cent, which is the proportion 

 of 4-per-cent milk required to make 3.2-per-cent milk. 



80 per cent of 100 pounds = 80 povmds, the required 

 pounds of 4-per-cent milk. 



100 — 80 = 20, the required pounds of skim milk. 



II. (a) To obtain milk containing 4 per cent of fat from 

 milk containing 3.2 per cent of fat by the extraction of skim 

 milk. 



X is — /' ) 



— ^^ = pounds of skim milk to be removed. 



s 



When r = the per cent of fat in the known milk, 



5 = the per cent of fat in the standardized milk, 

 X = the pounds of known milk. 



By substituting in the formula 



OC (a. — "^ 2 ) 



— ^ ^^^ = 0.2 .V = pounds of skim milk to be removed. 



4 



By removing from a given quantity of 3.2 per cent 

 milk, skim milk equal to 0.2 of the weight of that milk, 

 4-per-cent milk will be obtained. 



