194 Sweetened Condh;nse;d Milk Defeicts 



few days after manufacture, only a few of these large crystals 

 may appear in some of the cans. In the course of a few weeks, 

 all of the cans may contain specimen of these "rice crystals" 

 which increase in number until the entire contents of the cans 

 are one mass of "rice crystals," rendering the milk unsalable. 

 The direct causes of this particular kind of sugar crystallization 

 are excessive concentration of the condensed milk, the use of 

 too much steam pressure in the coils and jacket when condensa- 

 tion is near completion, delay in the drawing off of the condensed 

 milk from the pan, and leaky steam valves in the pipes leading 

 to jacket and coils. 



Toward the end of the condensing process the milk becomes 

 heavy, thick and syrupy, and boils with much less violence. If, 

 at this stage of the process, excessive steam pressure is used in 

 the jacket, and coils, the milk is superheated, often causing the 

 precipitation of "rice crystals." Again, where the finished con- 

 densed milk is drawn from the pan very slowly, either owing to 

 too small an outlet in the bottom of the pan, or because the milk 

 is forced to run through a strainer attached to the outlet, or 

 because the finished condensed milk is retained in the pan as 

 the result of an accident, in all of these cases there is danger 

 of superheating, and therefore, of the production of these large 

 crystals. This danger is especially great, where the valves of 

 the steam pipes leading to the jacket and coils are leaking, as 

 is often the case. The avoidance of excessive concentration and 

 the removal of any conditions that tend to expose the finished 

 or the nearly finished condensed milk to excessive heat will 

 usually prevent further trouble of this sort. 



Improper Cooling. — The method used for cooling the sweet- 

 ened condensed milk after it leaves the vacuum pan is another 

 important factor determining the smoothness or grittiness of the 

 finished product. The chief principles involved here are the 

 rapidity and extent of cooling and the amount of agitation to 

 which the condensed milk is subjected. 



In order to fully appreciate the importance of strict atten- 

 tion to details in the cooling process of sweetened condensed 

 milk, it should be understood, that the formation of sugar crystals 

 in concentrated solutions is enhanced by sudden chilling and 

 by excessive agitation of these solutions. The sudden and irreg- 



