UNSWEETENED CONDENSED MII.K DEFECTS 269 



temperature to which the cans are exposed at the high altitude 

 is high. 



This type of swelled cans obviously has nothing to do with 

 the quality of the contents, nor is it the result of fermentation or 

 chemical changes. It is caused by the fact that the pressure in 

 a can sealed at the sea level is somewhat greater than the atmos- 

 pheric pressure surrounding the can when transferred to a high 

 altitude. If, at the same time, the milk packed at the sea level 

 goes into the can at a low temperature and the -atmospheric 

 temperature at the high altitude, to which the sealed cans are 

 shipped, happens to be high, the difference in pressure between 

 the interior and exterior of the can is further increased, due to 

 the expansion of the milk and of the air in the can. The com- 

 bination of these factors is sufficient to cause the ends of the can 

 to bulge, making it erroneously appear that the package contains 

 fermented goods. 



This has actually happened in the case of one factory filling 

 a Government war contract, the whole shipment of evaporated 

 milk being rejected by the Government, because of the bulged 

 cans. 



Occurrences of this type can be prevented by filling cans, 

 intended for markets in high altitudes, with the evaporated milk 

 while warm. 



Brown Evaporated Milk. 



General Description. It is the aim of the processor to so 

 govern the sterilizing process as to give the evaporated milk a 

 rich, yellow ; creamy color. Frequently, this color limit is over- 

 stepped to the extent of imparting to the evaporated milk a brow r 'n 

 color, suggesting coffee with milk in it. In this condition evap- 

 orated milk fails to appeal to the consumer. 



Causes and Prevention. The dark color in evaporated milk 

 is due to the oxidizing action of excessive heat on the milk sugar, 

 causing the milk sugar to caramelize. This can be avoided by 

 reducing the sterilizing temperature, or shortening the sterilizing 

 process, or both. The storing of evaporated milk at high temper- 

 atures (summer heat) also tends to deepen its color with age. 



