EVAPORATION OF FRUITS. 



53 



open, in which case the loss of sugar by dripping will seriously lower 

 the quality of the dry product. As nearly as can be stated in definite 

 terms it is safe to start with a temperature of 130° to 140° F., grad- 

 ually raising it until the fruit is finished at 155° to 165° F. 



As with other fruits, the time required in which to dry prunes 

 varies with conditions, but from 24 to 30 hours is a conservative 

 average. 



The fruit is dry when the skin is well shrunken in the manner 

 familiar to all users of prunes. The texture should then be firm 

 but springy and pliable enough to yield readily when pressed in 

 the hand. The drying should not continue until the individual 

 fruits rattle as they are brought in contact with one another in han- 

 dling. It is true, however, that when the bulk of the fruit has 



Fig. 15. — Exterior view of a prune evaporator in Oregon. The dipper and sizer are 

 placed in the annex with shed roof. The compartments in which the fruit is dried 

 are in the main part of the huilding. 



reached the proper degree of dryness some specimens will be too 

 dry while others will contain an excess of moisture, as is the case 

 with other fruits. The condition is equalized in the same manner 

 as with apples and peaches, by placing the prunes in a pile when they 

 come from the evaporator, and working them over from time to time 

 until uniformity of product is reached. This may require from 

 several days to two or three weeks. 



Instead of piling the fruit in bulk, it may be put in boxes of con- 

 venient capacity to handle and poured from one to another every 

 day for a time while the fruit is curing or conditioning. Before the 

 fruit is conditioned, however, the " bloaters " and " frogs " should be 

 removed. 



In drying, prunes shrink in weight on an average about three to 

 one, i. e., about 3 pounds of fresh fruit are required to make 1 pound 

 of the dried product. 



