2816 



PRUNE 



PRUNE 



and Alaska. When the fruit is to be evaporated, it is first 

 allowed to ripen on the trees and should not be gathered 

 until it drops naturally to the ground (Fig. 3197), or 

 will drop with very little shaking. The fruit is picked 

 from the ground in bushel boxes, the pickers going 

 through the orchard every few days to gather it up. 

 The yield varies tremendously, from 1,000 to 8,000 

 pounds to the acre. As soon as the fruit is gathered, 

 it should be hauled to the evaporators and evaporated 

 quickly in order to avoid brown-rot, which often spreads 

 rapidly in the containers. 



There are two main types of evaporators used for 

 drying fruit, steam and hot air. The steam driers 

 are used only where a very large output is obtained. 

 It is customary for most of the orchardists to dry 

 their own fruit. Since the orchards on the whole are 

 rather small, an inexpensive building is used for the 

 process, and the hot-air type of building is erected. 

 These hot-air driers are of two distinct types, the 

 tunnel, and the stack. There are many forms of tunnel 

 driers. These tunnels consist of groups of long nearly 

 horizontal pipeways, built over a fire pit. They vary 

 in length from 25 to 50 feet. Each tunnel in itself may 



are also provided. These should be in below the vent 

 pipes so as to furnish fresh air rather than to assist in 

 rapidly sucking out the warm air. There is a very close 

 relation between ventilation, air-circulation, and the 

 humidity of the atmosphere. Such relationship, unfor- 

 tunately, has not been well studied by the larger number 

 of those operating the evaporators. 



The temperature is gradually increased during the 

 drying process, starting in the neighborhood of 125 to 

 135 and finishing at 160 to 180. It requires about 

 thirty-six hours on the average to dry prunes well, the 

 time depending on the building, ripeness of the fruit, 

 and atmospheric conditions. The fruit will generally 

 produce about twenty pounds of dried fruit to a bushel 

 of fresh. Before the prunes are placed over the heat, 

 it is customary to wash and grade the fruit. The more 

 modern buildings now have automatic machinery 

 which does all of this labor in one process. The prunes, 

 after being sorted, are dipped into boiling lye. This is 

 generally at the strength of one pound of lye to thirty to 

 fifty gallons of water. This use of lye is adopted solely 

 for the purpose of checking the skin of the fruit so 

 that the gases can escape more readily and the prune 



BULK BASIS 



30 to 35 



35 to 40 



40 to 45 



45 to 50 



50 to 55 



55 to 60 



60 to 65 



65 to 70 



70 to 75 



75 to 80 



80 to 85 



85 to 90 



90 to 95 



95 to 100 



100 and over. 



13*2 



15-8 



1J42 



3J44 



514514534514 



3^3143^3^3543343344 



5J4514554 



43^414454 



3143J43543M3543543344 



5545545346 



33433435431435435*3344 



3J4 334 354 334 354 3i<{ 



634634 



4^45445*434 



434 434 4 54 43i45445 



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be complete, or they may all be connected. The ten- 

 dency in the past has been to have the tunnels too long. 

 In the newer buildings, however, are tunnels from 16 to 

 25 feet in length. The capacity of the drier can be 

 increased more satisfactorily by increasing the num- 

 ber of tunnels rather than by increasing the length of 

 the tunnels. The heat pit is found directly below the 

 tunnels and, as a rule, brick arch furnaces, or iron 

 stoves, such as are commonly known as the hop stoves, 

 are employed. In order to distribute the heat more 

 uniformly, it is generally conducted from the furnaces 

 by long pipes ranging from 9 to 15 inches in diameter, 

 decreasing the farther they get away from the source of 

 heat. 



The stack drier is arranged to contain trays which are 

 placed one over the other, the bottom of the stack being 

 open. A single stack consists of three or four small 

 vertical compartments generally open to each other. 

 The fruit is first placed in the top compartment and 

 after slightly drying is removed and placed in a lower 

 compartment. The stack driers turn out a very good 

 product, but require a maximum amount of labor. 

 The buildings should be very well ventilated; these 

 ventilators should be of an adjustable nature so that 

 they can be opened and closed quickly. Cold air intakes 



be more easily dried. In most cases, as good results 

 could be secured by boiling water. There are probably 

 cases, however, when the skin of the fruit is so thick 

 that it is difficult to secure as quick and satisfactory 

 results without the use of lye. As soon as the prunes 

 have been dipped into the lye, they are quickly dipped 

 into clean water. A chemical analysis of the rinsing 

 waters has shown that they are generally acid rather 

 than alkali and it is very doubtful whether lye remains 

 on the fruit any length of time or, if it does, it is not 

 sufficient ever in any way to be injurious to the health. 

 As soon as the prunes have been thoroughly dried, 

 they are taken from the driers and stored in large bins 

 and allowed to sweat. They are then ready for the 

 processing. The processing is largely a steaming oper- 

 ation. This is generally done in central buildings 

 owned or controlled chiefly by the buyer or packers. 

 The prunes are submitted to the steam for a very short 

 time. This steaming cleans and sterilizes the fruits and 

 adds luster to the products. They can be so handled as 

 to add considerable weight. When this is done, how- 

 ever, it is unscrupulous on the part of the packer and 

 will sooner or later lead him into trouble. The proces- 

 sing of the prunes also softens them so that they can 

 be packed more easily. Formerly some bleaching was 



