SCIENCE AND INDUSTRY. 
Tt is also true that samples of dehydrated vegetables, with a moisture 
content of approximately 10 per cent., showed no deterioration when 
stored in a refrigerator at a temperature varying from 32 to 40 degrees 
Fahr.; while the same samples would show a very marked deterioration 
when stored a like period of time at a room temperature of 70 to 80 
decrees Fahr. The cost of refrigeration makes this method imprac- 
ticable. 
This deterioration, as previously stated, is not associated with bacteria 
for moulds, but may be attributed to the action of oxidases or enzymes. 
The destruction of these enzymes should, therefore, prevent this deteriora- 
tion. Enzymes are as a class easily destroyed by heat, and, therefore, by 
blanching or slightly pre-cooking the vegetable before dehydration, the 
enzymes present are destroyed. This is accomplished by dipping the 
vegetables in boiling water or steaming a short length of time before 
drying. This treatment has proved very effective in preventing this 
type of deterioration, and is now in use by practically all of the dehy- 
dration plants. Blanching or processing with steam or hot water is an 
art rather than a science. As manufacturers master this art, the 
products will improve in quality. Several factors will always influence 
the method and the time used, for instance, the product, the manner im 
which it is cut or sliced, and in some cases the variety and state of 
‘maturity. Insects, particularly moths, were a serious menace to the 
dehydration industry last year. The moth commonly found in infested 
products is known as the “Indian meal moth.” In co-operation with 
the Bureau of Entomology, United States Department of Agriculture, 
we have outlined apparently successful methods of control. The usual 
practice in dehydration plants had been to store the dehydrated products 
in open bins previous to packing. This practice offered an excellent 
opportunity for the adult moth to deposit eggs on the dehydrated 
products, which eggs developed into larve after packing. By packing 
immediately after dehydration in moth-free rooms, or storing in moth- 
tight bins, the deposit of eggs is practically eliminated. Infestation 
may occur later, however; when dehydrated products are stored in 
ordinary cartons, the larve of the moth may gain access to the material 
through the crevices of the package. Packing in a moth-proof carton 
would, therefore, be highly desirable, although the principal point of 
infestation is before packing. 
The keeping qualities of dehydrated vegetables have been greatly 
improved by controlling these two types of spoilage. Improved 
operating conditions and attention to details have largely eliminated 
the scorched, overdried, unpalatable product of the past. One practice 
—the use of sulphur dioxide fumes—has been practically eliminated in 
vegetable drying. The reason is simple. The sulphurous acid 
obseured and destroyed the delicate flavour of the vegetables. 
During the war, dehydration plants were principally concerned with 
the dehydration of vegetables. Since the war, however, when located in, 
a fruit-producing region, these plants have given much attention to 
the dehydration of fruits. This is particularly true on the Pacific 
coast. Dehydration plants have been able to produce products decidedly, 
superior in quality to the ordinary sun-dried or evaporated fruit. These 
“dehydrated” fruits (as the producers choose to call them) have .a 
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