4 CIRCULAR 619, U. S. DEPARTMENT OF AGRICULTURE 



acreage to take care of the needs of a plant at a price which will permit 

 both the grower and the drier to make a profit. 



SELECTION OF MATERIAL 



Material to be dried must be carefully sorted so as to be free of mold, 

 decay, and other defects that would lower the grade of the finished 

 product. The stone fruits (apricots, peaches, cherries, and plums) 

 must be sufficiently firm to permit mechanical pitting without tearing. 

 Where they are prepared by manual labor, they must not be so soft 

 as to stick to the trays. Apples and pears must not be so soft as to 

 crush in the coring and peeling machines. Berries, cranberries, and 

 grapes are usually dried whole. Fruit that needs trimming must be 

 avoided, as it not only adds to the cost of operation, but also lowers 

 the grade of the final product. Vegetables, such as beans (snap), 

 cabbage, carrots, celery, corn, parsnips, potatoes, pumpkin, spinach, 

 squash, and turnips, are sliced, shredded, diced, or cut in desired pieces 

 before drying. 



Dehydration does not improve the quality of fresh fruits or vege- 

 tables, nor does it provide for the satisfactory use of unsound products. 

 At best the process can only conserve the original constituents of the 

 foods, minus replaceable water. 



PREPARATION OF MATERIAL 



Careful handling reduces labor and waste. Bruised tissue is espe- 

 cially susceptible to discoloration and decay. Individual pieces pre- 

 pared from good stock are more uniform and attractive than those 

 from heavily trimmed stock. 



Washing 



Raw materials should be as carefully washed and cleaned for de- 

 hydration as for table use. Much of the washing machinery used in 

 canning is suitable for use in dehydration plants. A rotary cylindrical 

 washer equipped with a water-spraying system is very satisfactory 

 for washing many types of products. Soft or easily broken fruits 

 and vegetables may be washed by passing the trayed material between 

 several sprays of cold water. 



Grading for Size 



The segregation of fresh fruits and vegetables according to size 

 facilitates both the preparatory handling and the drying. 



One type of grader consists of a perforated metal plate, 3 by 10 

 feet, or larger. The perforations are in sections of varying size, and 

 the plate is inclined and mechanically agitated in order to insure an 

 even flow of the material in one direction. The product is separated 

 according to size by being passed through the perforations. Per- 

 forated plates are also used in stacks. Several plates, each stamped 

 with holes of uniform size, the holes varying in size with each plate, 

 are set one above the other, with 6 inches or more between plates. 

 They are arranged so that the holes are progressively smaller from 

 top to bottom. 



