SWEETENED CONDENSED MILK DEFECTS 223 



Sandy, Rough or Gritty Sweetened Condensed Milk. 



General Description. This is condensed milk in which a por- 

 tion of the milk sugar has been precipitated in the form <<f large 

 crystals, the size of the crystals depending on the conditions 

 causing crystallization. First-class sweetened condensed milk 

 is smooth and velvety. Such mjilk is not entirely free from sugar 

 crystals, but they are so minute in size that they do not rob the 

 condensed milk of its natural smoothness. In sandy or gritty 

 condensed milk the crystals are very numerous and large enough 

 to grind between the teeth, similar to salt crystals in gritty 

 butter. The presence of these crystals is also noticeable to the 

 naked eye; the milk looks candied.. 



Causes and Prevention. The sugar crystals which render 

 the condensed milk rough and sandy consist largely of milk 

 sugar. The solubility of milk sugar is relatively low. Milk 

 sugar requires about six times its weight of water at ordinary 

 temperature for complete solution. Condensed milk contains 

 from 12.5 to 15 per cent milk sugar and only about 26.5 per cent 

 water. The ratio of milk sugar to water in sweetened con- 

 densed milk, therefore, is 1 :2, while for complete solution it 

 should be 1 :6. The milk sugar in this product is present in a' 

 supersaturated solution and any condition which favors sugar 

 crystallization strongly tends to precipitate this milk sugar, 

 because there is more of it present in the milk than the available 

 water is capable of readily keeping in solution. The chief factor 

 that prevents the milk sugar from precipitating very badly is 

 the great viscosity of the condensed milk. This is largely due 

 to the caseous matter and the cane sugar. 



Cane Sugar Content. It has been argued that the large 

 amount of sucrose which sweetened condensed milk contains, 

 is the principal cause of sandy milk and of sugar sediment in 

 the bottom of the tin cans, and that a reduction in the amount 

 of sucrose lessens the tendency of the sugar to crystallize and 

 the milk to become sandy. This line of reasoning is erroneous. 

 The presence, in water, of sucrose in solution does not materially 

 lessen the power of the water to dissolve milk sugar, provided 

 that the sucrose solution is not a saturated one. Sweetened 

 condensed milk, contains about 35 to 45 per cent sucrose and 



