324 CoMPOSITION AND PROPERTIES OF MiLK POoWbERS 
than the film-process powders, hence the former should go in solu- 
tion more rapidly than the latter. 
The above facts concerning the relation of fineness and flakiness 
of milk powder to ease and speed of solution prevail to a certain 
point. When that point is exceeded mechanical handicaps enter 
into the results that tend to retard solution, at least in the beginning. 
In the case of excessively fine and flaky milk powders, the exposed 
surfaces are so great and the particles so small that when the powder 
is placed into water, the rapid solution of the powder that comes 
into immediate contact with the water causes the powder to run 
together and paste, forming a pasty coating around the remainder 
of the powder. This coating hinders and retards the penetration of 
the powder by the water and thereby renders complete solution 
slower, at least at the start. 
This difficulty is generally not experienced with the film-process 
powders, which are of a granular nature. It can be largely avoided 
in the case of the spray-process powders by so adjusting the orifice 
of the spray nozzles and the pressure of the milk, as to increase the 
coarseness of the spray. The coarser the spray the less flaky and 
the more granular the powder. High pressure and small orifice in 
spray nozzles produce a very fine spray and a flaky powder. Low 
pressure and large orifice in spray nozzles produce a less fine spray 
and a more granular powder. 
The concentration of the milk at the time of spraying also in- 
fluences the coarseness or fineness of the spray to a considerable 
extent. Other conditions being the same, the higher the concentra- 
tion of the milk at the time of spraying the coarser the spray and 
the less flaky and the more granular the resulting milk powder. 
When the milk is sprayed before previously condensing it, a finer 
and flakier powder is produced than when the milk is first con- 
densed at the ratio of about 4:1, and the condensed milk is sprayed, 
always assuming, however, that other conditions, such as orifice of 
spray nozzle and pressure of milk be the same. It is possible, even 
by spraying the fluid, uncondensed milk, to produce a powder that 
is distinctly granular, by the proper adjustment of the above factors. 
The miscibility of the dried milk with water depends, aside 
from its solubility, readiness of solution and character of the protein, 
on the physical condition of its butter fat. If the process employed 
is such as to destroy the globular form of the fat globules, it is 
