Condensed Miek and Miek Powder 113 



the tinplate to become dull and the contents to' acquire a disagree- 

 able metallic flavor. When stored for an excessively long time this 

 chemical action may be sufficient to cause the evolution of consider- 

 able quantities of hydrogen gas, swelling the cans. 



Sweetened condensed milk which is preserved by about 40 per 

 cent, of sucrose, will keep apparently unchanged for a considerable 

 length of time. It is best, however, when fresh. Bacteriological 

 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 develops a stale flavor. 

 White and yellow "buttons," lumps, or nodules of a cheesy texture 

 and flavor, probably due to some fungus growth, are also 1 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 con- 

 densed 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 temperature. 

 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 temper- 

 ature 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 dis- 

 appears when the contents of the cans dissolve again, yet the swell- 

 ing 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. 



