226 SWEETENED CONDENSED MiiK DrFecrs 
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. 
Experimental results by C. S. Hudson,! on the solubility 
and crystallization of milk sugar also show that milk sugar 
crystals of large size were obtained by evaporation of a solution 
of milk sugar at 95 degrees C. (203 degrees F.). 
Excessive Concentration.—In as much as the initial cause 
of the precipitation of a portion of the milk sugar which leads to 
the production of sandy condensed milk lies in the fact that the 
milk sugar is present in this product in the form of a super- 
saturated solution, it is obvious that the danger of sugar crystal- 
lization and sandiness in this product increases with the increase 
in concentration. This is fully borne out by practical experience. 
The higher the ratio of concentration the more difficult it be- 
comes to manufacture a smooth condensed milk. The danger 
here is further augmented by the fact that in the very highly 
concentrated product the tendency of superheating 1s augmented. 
And the superheating gives rise to very large crystals which 
render the product exceedingly coarse. The superheating is 
due to the increased sluggishness of the very thick condensed 
milk in the pan, it ceases to boi! vigorously enough and is there- 
fore excessively exposed to the hot coils. It is further due to 
the slowness with which this product leaves the hot pan. 
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- 
o. ee ee Se Tees of Milk Sugar in Solution, Jour. Am, Chem. 
Soc., Vol. XXVI, . 9, 1904 
