18 MASS. EXPERIMENT STATION BULLETIN 404 



pronounced hay-like odor. Similarly, carrots will lose almost all of their color 

 and develop a musty flavor and odor which makes them practically inedible. 



With present equipment shortages, particularly in the home, blanching equip- 

 ment must be improvised. The best procedure for the blanching of most veg- 

 etables is to have the product already' spread on the trays, and to subject the whole 

 tray to the steaming process. This can be done in a large kettle, or other vessel of 

 sufficient size which can be fitted with a relatively tight cover. Approximately 

 two inches of vigorously boiling water provides ample steam, and a light rack of 

 either wood or wire serves to keep the trays above the level of the boiling water. 

 The trays are stacked one above the other in such a manner that the steam 

 has intimate access to all parts of the tray. This is of extreme importance, since 

 adequate and uniform blanching is a requisite for quality products. Every piece 

 must be heated through to the center. Because of this fact, and the limited height 

 of the average vessel, not more than three trays of material should be blanched 

 at once. It must also be stressed that the water be vigorously boiling during the 

 entire blanching period. Since the size of the individual pieces has a direct re- 

 lationship to the length of blanching period required, it is advisable to keep the 

 size of the pieces within the lim.its specified under the individu?l products for the 

 blanching periods recommended. Exceptions to this procedure are corn and beets. 

 Corn should be blanched in boiling water on the cob, cooled, and the kernels 

 then sliced ofi^ and trayed. Beets should be blanched whole in boiling water, 

 peeled, and then subdivided. Compensation for these factors is made in the 

 recommended blanching times. 



If no vessel large enough to hold a tray is available, the product must be 

 blanched before traying. This can be accomplished by an arrangement similar 

 to that for the trays, but instead of the trays a wire basket, strainer, or similar 

 container for the product is placed on the rack and subjected to the steam. Only 

 a light laj'er of product should be put in the container at one time, and it should 

 be loosely spread. For a common eight-quart kettle the batches each time 

 should be no larger than the individual tray load of the product. The advan- 

 tage of this is twofold, since it not only helps prevent exceeding the steaming 

 capacity of the vessel, but also assures proper tray loads, since a considerable de- 

 crease in volume, particularly with leafy vegetables, occurs when they are 

 blanched. With some products it maj' be necessary to stir up the material once 

 or twice during the blanching period to assure complete heating of all the product. 

 This is important, since all pieces must be uniformly and thoroughly heated. Also, 

 care must be taken to spread the blanched material uniformly over the tray and 

 prevent clumping of the pieces. Clumping will greatly retard the escape of 

 moisture during the dehydration process. 



Dehydrating 



It is recommended that the same amount of heat be used throughout the entire 

 period. While it is possible to vary the temperature somewhat, using higher 

 temperatures during the first part of the drying process, the decrease in time re- 

 sulting from such practice is negligible in the long run. Furthermore, there is 

 decided danger of harm to the product, since it is difficult to readjust the tempera- 

 ture during the latter stages of drying when the products are most sensitive to 

 heat. 



Experimental studies have shown that a temperature of 145° F. is the most 

 satisfactory for dehydration of the common vegetables in the home. A good 

 thermometer with a range up to 212° F. should be kept in the dehydrator through- 

 out the drying period, preferably on one of the middle trays. Before use, the 



