2 BULLETIN 1335, U. S. DEPARTMENT OF AGRICULTURE 
The outstanding advantage of drying as a method of preserving 
foods is that the weight and bulk of the products are greatly reduced, 
thus making possible economy in storage and transportation. This 
saving will become more significant as the need for food conserva- 
tion in the United States increases. The production cost of de- 
hydration compares favorably with that of canning, and no cases of 
food poisoning, such as botulism, have beeh traced to dried foods. 
Dried fruits and vegetables are as convenient for use in the home 
as the fresh products. They need no peeling or other preliminary 
treatment, and soaking and cooking can usually be combined. 
Only the quantity required need be used at one time; the rest will 
keep in good condition. 
Two objections to the use of dehydrated foods still exist. They 
require soaking and cooking and they do not always reach the 
consumer in good condition. There is no evidence at present that 
the first objection can be overcome. The second objection, how- 
ever, will undoubtedly disappear as familiarity with dried foods 
increases the demand for them. 
DEHYDRATION INDUSTRY 
‘“ Dried,’ “sun-dried,”’ ‘“‘evaporated,’’ and ‘“‘dehydrated”’ are the 
terms most commonly used to describe dried products. ‘‘ Dried”’ in- 
dicates drying by any means; ‘‘sun-dried’’ indicates drying without 
artificial heat; and ‘‘evaporated’’ implies the use of artificial heat. 
To-day the term ‘‘evaporated”’ refers more particularly to the use 
of artificial heat in driers depending for their air circulation on natural 
draft, while ‘““dehydrated’’ imples mechanical circulation of artifi- 
cial heat. 
The commercial dehydration of fruits has reached a more ad- 
vanced stage of development than has the commercial dehydration 
of vegetables, owing largely to the fact that the public is familiar 
with sun-dried and evaporated fruits, whereas it knows compara- 
tively little about dried vegetables. Fruit drying in the United 
States is confined almost entirely to California, the Pacific North- 
west, and western New York (Table 1). The prunes in the Pacific 
Northwest and the apples were dried almost exclusively by evapora- 
tion, but practically all the rest of the fruit listed in Table 1 was 
sun dried. The dehydration of prunes and other fruits is becoming 
more extensive (Table 2). 
During the World War 8,905,158 pounds of dehydrated vege- 
tables, divided as follows, were shipped to the United States Army 
overseas: Potatoes, 6,437,430 pounds; onions, 336,780 pounds; 
carrots, 214,724 pounds; turnips, 56,224 pounds; and soup mixture, 
1,860,000 pounds. ; 
Table 3 shows the extent of the dried-vegetable industry in this 
country in 1919. All the vegetables were either dehydrated or 
evaporated. 
DEHYDRATION PLANT 
To be successful a dehydration plant must be built where fresh 
materials are plentiful and reasonable in price. A diversity of 
products makes possible an operating season long enough to kee 
the overhead expenses down to the minimum. The products dried, 
however, should be limited to those for which a ready market exists. 
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