SWEETENED CONDENSED Mink 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 1s 
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. lf 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 wash 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 DesScription.—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. 
