COMMERCIAL DEHYDRATTOX 



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method consists in inserting a tube from a cylinder of gas into a can 

 already filled with dehydrated food (fig. 9). A measured amount of 

 gas flows through the tube, displaces the air, and fills the can in one 

 operation. A can may be filled with carbon dioxide gas by placing an 

 exact amount of finely ground solid carbon dioxide (dry ice) in the 

 bottom just before the food is put in. Gas is generated directly from 

 the solid material and pushes the air out of the can. 



Figube9. — Replacing air in a can of dehydrated cabbage with an inert gas, which 

 flows through the tube to the bottom of the can. The gas atmosphere prevents 

 oxidation, which would result in loss of color, flavor, and vitamins. 



Packages for dehydrated foods must keep the contents dry by ex- 

 cluding water and moisture vapor, must keep out insects and protect 

 from damage by rodents, must be easily sealed, and must stand up 

 under rough handling — an especially important point in shipments 

 to battle fronts. The common "tin" can, which is composed almost 

 entirely of steel, fulfills all these conditions. Substitute packaging 

 materials being tested are paper treated to resist moisture vapor; 

 moistureproof cellophane; simple laminations of paper and cello 

 phane; and compound laminations of paper, cellophane, and metallic' 

 foils. Containers made of these materials must be readily sealed by 

 application of heat, free of such defects as pinholes and cracks, and 

 heavy enough to withstand some hard knocks. None of those yet 

 developed are absolutely moisturc-vapor-pioof. 



The keeping quality of a dehydrated food is closely related to its 

 degree of dryness. The objective in packaging and storage should be 

 to maintain as low a moisture content as possible. Experiments with 

 dehydrated cabbage stored at 90° F. have shown that storage life, 

 measured by (he retention of vitamin C, is increased 50 percent tor 



