SWEETENED CONDENSED MILK DEFECTS 251 



grees F.) the condensed milk will break down rapidly with age, 

 usually developing a putrid flavor and odor. This defect rarely 

 appears where the fresh milk is heated to 180 degrees F. or 

 above. This phenomenon is probably due to the presence in 

 milk of active enzymes, such as galactase, gradually decompos- 

 ing the proteids. The action of most of these enzymes is 

 destroyed when the milk is heated to 176 degrees F. or above. 



Metallic Sweetened Condensed Milk. 



General Description. Sweetened condensed milk frequently 

 is pregnant with a very distinct metallic flavor suggesting copper. 



Causes and Prevention. This can usually be traced back to 

 an unsanitary condition of the dome of the vacuum pan. The 

 sugar and acid in the boiling milk in the pan tend to cause the 

 formation of copper oxide and copper salts, on those sections of 

 the interior surface of the pan which are not daily completely 

 cleansed. 



The dome of the pan is neglected in many condenseries from 

 the standpoint of thorough cleaning. If it is permitted to go 

 uncleansed for a considerable period of time, it becomes coated 

 with copper salts and when the pan is again in operation, the 

 boiling milk and its spray \vash these metallic salts down, incor- 

 porating them in the condensed milk. 



That the copper in the dome is being acted on can be very 

 readily determined by wiping the inside surface of the dome off 

 with a wet sponge, then analyzing the expressed liquid that 

 the sponge has absorbed. This liquid will be found to contain 

 varying amounts of copper, according to the state of cleanness 

 of the dome. 



In order to avoid metallic flavor in sweetened condensed 

 milk, the dome should be washed down daily with similar care 

 as is given the cleansing of the jacket, body and coils, and each 

 morning, before the milk is allowed to enter the pan, the entire 

 pan, including dome and gooseneck, should be thoroughly rinsed 

 down with plenty of clean water. 



Brown Sweetened Condensed Milk. 



General Description. Some of the sweetened condensed 

 milk on the market has a brown color, suggesting chocolate pud- 

 ding. In this condition it is usually rejected by the consumer. 



