156 
Journal of Agricultural Research 
Vol. XXXI, No. 2 
held at a temperature other than that of effective refrigeration. An 
efficient egg-drying process, therefore, must provide for the imme¬ 
diate chilling or freezing of the broken-out product or for its prompt 
dehydration. 
In the course of dehydration the products are subjected to contact 
with heated air, which removes, partially at least, the volatile con¬ 
stituents. This removes or changes the odors characteristic of the 
fresh sound product and reduces or destroys the odors in low-grade 
eggs incident to spoilage, which would readily be recognized in the 
liquid egg. The odor of commercially dried eggs, therefore, may be 
expected to differ sufficiently from that of the fresh product to re¬ 
quire careful examination by experienced analysts. 
The odor, appearance, and taste of dehydrated egg differ so 
markedly from those of fresh liquid egg that extensive experience is 
necessary to coordinate the two kinds of egg. 
In planning a bacteriological examination of dehydrated eggs, all 
of these factors must be taken into consideration. Theoretically, 
the number of living bacteria in the finished product depends on the 
number and kind of bacteria in the liquid product, the temperature to 
which the product is subjected, and the length of time at which that 
temperature is maintained. Furthermore, in view of the fact that 
most of the dried eggs used in this country are imported, the effect 
of the time and conditions of storage upon the bacterial count becomes 
important, if that count is to be used as an index of quality. 
It is believed that the air is an unimportant source of contamina¬ 
tion under proper conditions in the factory. This is certainly true 
of the processes studied in this investigation. Likewise, the amount 
of contamination from utensils is insignificant, if they are clean and 
dry. If the utensils are wet or improperly cleaned, however, the 
product will have more organisms in the portions in contact with 
such contamination. From the bacteriological standpoint, the 
moisture content of the dried product, and the evenness of the dry¬ 
ing, are the factors which must be closely watched if a desirable and 
uniform product is to be obtained. 
Two dehydration processes for eggs—the spray and vacuum-drum— 
were studied by the Bureau of Chemistry, United States Department 
of Agriculture, in the summers of 1922 and 1923. In both of these 
processes liquid egg was dried to a powder of low moisture content in 
a short time. Bacterial action during this short drying period was 
considered negligible. The content of living organisms in the egg 
powder represents the effect of the temperature, time of exposure at 
that temperature, and degree of the concentration of the product 
upon whatever organisms were initially present. 
SPRAY PROCESS 
GENERAL PROCEDURE 
In the spray process, the first method studied, the egg was exposed 
to a temperature of about 75° C. for 18 to 25 minutes. Briefly, this 
process consisted in forcing liquid egg, under great pressure, through 
a fine spray apparatus, into a collecting chamber in which dehydration 
was accomplished by exposure to a large volume of heated air. The 
egg particles remained exposed on the floor of the heated chamber 
for the period of the “run,” approximately 20 minutes. 
