Introduction 



storage. Whenever the temperature rises during 

 storage, if conditions are right, it gives the lactic 

 acid-forming bacteria a chance to develop. This is 

 especially true of fluid or liquid milk and unsweetened 

 condensed milk. These products sour quickly in a 

 refrigerator that is not held at a uniform cold 

 temperature. 



The Influence of Humidity on Dairy Products. 



Humidity is most important in the ripening of 

 cheese, the manufacture of milk powder and the 

 storage of products not hermetically sealed. The 

 correct humidity is necessary for the proper func- 

 tioning of the ripening agent during cheese curing. 

 If the humidity is too low, there will be too much 

 evaporation, which will cause unnecessary losses. If 

 too high and accompanied by the correct tempera- 

 ture, molds will grow and spoil the product. If the 

 humidity is too high, it is impossible to make good 

 milk powder after certain processes. 



The Influence of Pressure on Dairy Products. 



It is very necessary to have a constant steam 

 pressure for the successful operation of many ma- 

 chines. For example: the centrifugal separator. If 

 there is not sufficient steam pressure, the efficiency of 

 the machine is reduced. It is also important to have 

 different materials put through machines at a given 

 pressure. For example: ice cream mixed through 

 the homogenizer. If the pressure is reduced, the in- 

 tended results are not accomplished. The important 

 subject of power-plant efficiency will be discussed in 

 a separate chapter. 



As stated above, the quality and salability of 

 dairy products depend upon a careful regulation of 

 temperature, pressure and humidity. Manufactur- 



