DEHYDRATION OF VEGETABLES 19 



dehydrator, with the trays in place, shuuld be heated to the drying temperature 

 and kept at that temperature, by proper adjustment of the heat, for 10 to 15 

 minutes in order to make sure that an even heat can be maintained. When an 

 electric heating element is used in the forced air unit, the heat is regulated by 

 variation of the number of fresh air apertures. If the dehydrator has been 

 properly constructed, the temperature during this period should not show a 

 variation of more than two degrees between any of the trays. When the tem- 

 perature has been adjusted, the trays can be removed and prepared. As little 

 time as possible should elapse between the time the material is prepared, blanched, 

 and placed in the dehydrator. 



In loading the dehydrator the trays should be alternately staggered to form a 

 channel for circulation of the air. When the trays are first put in, the tempera- 

 ture may drop as much as 20 to 30 degrees because of the change in humidity 

 conditions and the heat required to bring the temperature of the trays them- 

 selves up to the temperature of the drying air. However, the original heat adjust- 

 ment must not be changed. Within a short time the temperature will go up to 

 within a few degrees of the original setting, but will not actually reach this point 

 until the product is nearly dry owing to the presence of the water vapor being 

 carried off by the air. Because the moisture is carried off through the chimney in 

 the natural draft dehydrator, the humidity will always be higher at the top of 

 the cabinet, particularly during the early stages of the drying period. For more 

 rapid and uniform drying, therefore, the tray order should be reversed every two 

 hours during the operation. 



Determination of the Finish Point 



There is little danger of food becoming too dry and the lower the final moisture 

 content, the better Is the keeping quality of the product. In general, the final 

 moisture content of vegetables properly dehydrated in accordance with the 

 above procedure averages around 5 per cent, which is quite satisfactory. In this 

 condition the pieces are rigid and brittle, and leafy vegetables crumble to a powder 

 when squeezed In the hand. If the given procedure has been followed, a simple 

 test for the finish point consists of mounding up some of the dry material on the 

 trays and inserting the bulb end of the thermometer into the mounds. If, after 

 five minutes of continued heating with the thermometer In this position, the 

 temperature of the product on all the trays Is the same as that of the air, i.e., 

 145° F., drying is complete. There should be no soft or moist pieces on any ot 

 the trays. 



DIRECTIONS FOR DEHYDRATING INDIVIDUAL PRODUCTS 



It is not considered economical to dehydrate certain of the vegetables, and 

 those which are not ordinarily canned should not be dehydrated. Products 

 such as dehydrated potatoes and onions are recommended only for use in soup 

 mixes. 



Beets: Only tender beets, free from woodiness and of good color and flavor, 

 should be used. Cut away the greens, leaving approximately one-half Inch of 

 the stems, wash thoroughly, and blanch in boiling water for 30 minutes (or longer 

 if necessary so that the beets are cooked through). This is one instance In which 

 the product is not peeled and cut up before blanching, since that would cause loss 

 of color. The skin peels off easily after blanching is completed. Cool, trim off 

 the tops and roots, peel, and cut into three-sixteenth inch slices or shoe-strings. 

 Tray load should be 1 J^ to 1 J^ pounds. 



