CONDENSED MILK DEFECTS 225 



pipe in the condenser is very close to the goose neck of the pan, 

 as is the case with most of the vacuum pans in use, which are 

 equipped with horizontal spray condenser, the chilling of the 

 vapors and of the spray of milk rising from the pan is so 

 sudden, that sugar crystals are prone to form in the spray and 

 along the walls of the pan. These crystals either stick to the 

 side of the pan, or fall back into the milk where they later mul- 

 tiply and cause the milk to become sugary. Trouble from this 

 source can be avoided by either raising the temperature of the 

 water that goes to the condenser which is, however, not practical 

 under most conditions, or by closing the holes in that portion of 

 the spray pipe which is nearest the pan. This can easily be done 

 by wrapping a piece of galvanized iron or tinplate around the 

 portion of the spray pipe to be closed, or by filling the holes 

 with solder, or by replacing the old spray pipe by a new and 

 shorter one, properly constructed. 



Superheating at End of Batch. Sometimes the manufac- 

 turer is persistently troubled with the apprearance of crystals in 

 the condensed milk of monstrous size, as large as rice kernels ; 

 this condition arrives usually very gradually. During the first 

 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 



