THE Srray Process 305 
pre-condensing the milk before spraying. ‘The spraying of un- 
condensed milk appears to produce a more flaky powder while 
the spraying of condensed milk results in a more granular 
powder. The flake shape does not pack as closely together as 
the granular shape. This is obviously an advantage in favor of 
pre-condensing. 
However, the physical shape and condition of the powdered 
a 1 1 
milk can be controlled to a considerable extent by modification 
of the coarseness or fineness of the spray. In fact, by such modi- 
feation it is possible to make a distinctly granular product from 
uncondensed milk, and a decidedly flaky product from the pre- 
condensed milk. 
The finer the spray the more flaky the milk powder; the 
coarser the spray the more granular the milk powder. ‘The fluid 
milk makes a finer spray than the condensed milk; therefore the 
more flaky condition of the powder from the former. 
Aside from the concentration of the milk to be sprayed, the 
fineness or coarseness of the spray can he regulated by the size 
of the orifice of the spray nozzles and by the pressure of the 
milk. The larger the orifice or the lower the pressure, or both, 
the coarser will be the spray and consequently the more granular 
the milk powder. Therefore, in order to reduce the flakiness 
and bulkiness of milk powder made from uncondensed milk, and 
to make this milk powder more granular, the orifices of the 
spray nozzles must be relatively large or the pressure of the 
milk must be relatively low, or both. Superheating of the milk 
(boiling it at 212 degrees F.) by turning steam direct into it 
also assists in minimizing the fluffness and bulkiness of the re- 
sulting milk powder but it diminishes the solubility of the 
product. 
Effect of Pre-condensing on Keeping Quality of Spray Milk 
Powder.—Inasmuch as the spray milk powder that is now com- 
mercially manufactured dees not contain enough moisture, 
when properly desiccated and protected from dampness, to 
sustain bacterial action, the keeping quality of this product does 
not materially depend on bacterial decomposition or freedom 
therefrom. 
Milk powder does became stale with age, however. and 
much of it gradually develops a tallowy flavor and odor. This 
