56 Condensed Milk and Milk Powder 



parity of apparatus. All of these features are essential in the suc- 

 cessful condensing of milk. 



Rapid evaporation cannot take place until the milk is brought 

 to the boiling point and is kept there until evaporation is completed. 

 Under atmospheric pressure and at the sea level, the boiling point of 

 water is 212 degrees F., the boiling point of milk is very slightly 

 higher, about 214 degrees F. Evaporating of milk under atmos- 

 pheric pressure, however, is a relatively slow process, requiring a 

 long time, much fuel and large apparatus. Furthermore, exposure 

 of the milk to 212 to 214 degrees F. long enough to complete evap- 

 oration would render the product unsuitable for market. The prop- 

 erties of some of its ingredients are altered, the product would, as- 

 assume a dark color and 1 a marked cooked flavor, as (he result of the 

 effect of heat. All of these objections are minimized and partly 

 avoided by lowering the boiling point of milk. 



Relation of Pressure to Boiling Point. — The temperature 

 at which milk boils depends on the pressure to which it is exposed. 



