136 MISC. PUBLICATION 5 40, IT. S. DEPT. OF AGRICULTURE 



pounds per square inch at room temperature to a density of 60 pounds 

 per cubic foot. The cakes were reconstituted to a 6.5 percent juice 

 simply by beating with an egg beater and then adding boiling water 

 and heating 1 minute. The dry compressed cakes crush easily. # 



Dehydrated vegetables of diced, sliced, stripped, or flake form yield 

 high-density blocks that readily rehydrate and in which the content 

 of fines is low. Hydraulic presses have been used in obtaining the 

 results shown in table 13. The maximum pressure has been main- 

 tained for a period, or "dwell," of 1 minute. Blocking has been ef- 

 fected ordinarily at temperatures from 140° to 160° F. The purpose 

 of an elevated temperature is to produce a pliable state of the vege- 

 table for compression so that it will reach a high density without 

 breaking into small pieces to any considerable extent. Firm blocks 

 of somewhat lower densities have also been produced at ram speeds 

 of 1 to 2 inches per second followed by a "dwell" of 15 seconds. 



Fine material passing a 4-mesh screen, caused by compression 

 under the conditions shown in the tabulation, did not exceed 5 per- 

 cent of the rehydrated vegetables for any form of beets or carrots, 

 or for onions or rutabagas. In general, the cohesion of the block 

 was only fair at lower pressures and the same temperatures as those 

 listed in the table. Higher pressures were not required for good 

 cohesion nor were they necessary for adequate compression. 



A slight expansion of blocks one-half inch thick occurs in that 

 dimension when they are removed from the hot molds. This ex- 

 pansion is slight because these pieces cool rapidly. An estimate of 



Figure 68. — Sixteen 2-pound bricks in arrangement shown at right fill a 5-gallon 

 can with 800 servings of carrots. 



