STORAGE 153 



Sweetened condensed milk which is preserved by about 40 

 per cent, of sucrose, will keep apparently unchanged for a con- 

 siderable length of time. It is best, however, when fresh. Bac- 

 teriological examinations have shown that, while moderate age 

 does not change the outward appearance of this condensed milk, 

 the bacteria in it gradually increase and the milk gradually de- 

 velops a stale flavor. White and yellow "buttons," lumps, or 

 nodules of a cheesy texture and flavor, probably due to some 

 fungus growth, are also prone to appear in the condensed milk. 

 Age, also, causes it to become darker in color. These defects are 

 especially apparent in old milk which has not been kept at a 

 low temperature. Again, sweetened condensed milk made in 

 May and June has a strong tendency to thicken with age and to 

 become entirely solid. 



In some cases a part of the sweetened condensed milk made 

 during the summer months is stored in large cylindrical wooden 

 or iron tanks sunk into the ground, or installed in the basement 

 of the factory, where the condensed milk remains at an even tem- 

 perature. As the demand for the product increases and the 

 supply of fresh milk decreases, condensed milk is drawn from 

 these tanks to fill the increasing orders. 



Effect of Storage Temperature. Most, if not all the changes 

 which condensed milk is prone to undergo in storage are 

 retarded, if not entirely prevented, when stored at the proper 

 temperature. Temperatures of 60 degrees F. or above are too 

 high for satisfactory storage for a prolonged period of time and 

 the higher the temperature the greater the resulting defect. 



Temperatures below the freezing point of water are also 

 undesirable. The evaporated milk freezes and while so doing it 

 expands sufficiently to swell the cans. Although this swelling 

 disappears when the contents of the cans dissolve again, yet 

 the swelling action tends to weaken the cans and may give rise 

 to subsequent leakers. Again the melted evaporated milk is 

 prone to be grainy as the result of freezing. This is due to the 

 fact that when freezing, the watery portion separates from the 

 curd and the latter contracts. When the milk thaws up the curd 

 remains contracted and fails to form a smooth emulsion with 

 the remainder of the milk. 



