192 SwEETBiNED Condensed Milk Defects 



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 tlian the available 

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

 that prevents the milk sugar from precip'itating 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 argtied 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 3.S to 45 per cent, sucrose and 

 24 to 28 per cent, water. Sucrose dissolves in one half its weight 

 of water. The sweetened condensed milk does not, therefore, 

 contain a saturated solution of sucrose. 



The chief factors causing milk sugar crystallization and 

 sandy condensed milk are: incomplete solution of the sucrose, 

 excessive chilling in the vacuum pan, superheating in the vacuum 

 pan, improper cooling, excessive stirring, and warming up too 

 cold condensed milk with the help of agitation. 



Incomplete Solution of Sucrose. — Tf the finished product is 

 to be smooth and free from sandiness, it is essential that the 

 sucrose which is added to the hot, fresh milk be thoroughly dis- 

 solved before the mixture reaches the vacuum pan. Undissolved 

 sugar crystals in a medium as highly concentrated as sweetened 

 condensed milk have much the same effect in a physical way, as 

 have bacteria in fresh milk in a biological way; they multiply 

 rapidly. Therefore, if all the sugar added to the fluid milk is 

 not completely dissolved, the undissolved sugar crystals give 

 rise to wholesale precipitation of the milk sugar in this product 

 after manufacture. Complete solution of the cane sugar can 

 best be accomplished by heating the liquid, milk or water, in 

 which the sugar is to be dissolved, to the boiling point and by 

 boiling the mixture for several minutes ; or by placing the sugar 



