192 STORAGE 



few days at ordinary temperatures and should, therefore, be sold 

 and used as soon as possible after manufacture. If their storage 

 is unavoidable, they should be held as near the freezing point 

 as possible. For prolonged storage it might be advantageous to 

 freeze them. However, reliable data on this phase of the indus- 

 try are lacking. 



Evaporated milk, sold in hermetically sealed cans, is sup- 

 posed to be entirely sterile, and. if made properly, will keep in- 

 definitely. There is a constant tendency, however, for the fat 

 to separate out. which naturally is augmented by prolonged 

 storage. Again, the lactic acid in the evaporated milk gradually 

 acts on the can. causing the tinplate to become dull and the 

 contents to acquire a disagreeable metallic flavor. *When stored 

 for an excessively long time this chemical action may be suffi- 

 cient to cause the evolution of considerable quantities of hydro- 

 gen gas. swelling the cans. 



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, due to fungus growth, 

 are also prone to appear in the condensed milk. Age, also, causes 

 it to become darker in color. These defects are especially ap- 

 parent 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 marie 

 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. 



