VEGETABLE AND FRUIT DEHYDRATION 119 



able highest dew point can be estimated, the corresj)onding relative 

 humidity in the packing room at any desired temperature may be 

 determined from a humidity chart. (See p. 52.) 



Some dehydrators in dry areas find that they can raise the air 

 temperature in the packing room enough to avoid moisture absorp- 

 tion by the product. Warm air has a lower percentage of relative 

 humidity than cold air of the same dew point. Besides the method 

 just indicated, there are three methods commercially used for de- 

 humidifying air, all of which actually remove a part of the water 

 present. Silica and alumina gels are both used to absorb water vapor 

 from air to be dried. The gels are reactivated by the use of closed 

 steam pipes or electric heaters and a stream of air.- Refrigeration is 

 also used to condense moisture, which is separated thus from the 

 incoming air. Another method consists of absorption of moisture 

 in a spray chamber by special solutions, such as lithium chloride, 

 which are regenerated after use. Finally, one must bear in mind 

 that when the finishing and packing room is dehumidified by any 

 method which actually removes water vapor from air, it may be 

 practicable to remove some air from that room as the air feed to a 

 bin drier. 



FINAL INSPECTION OF THE DRY PRODUCT 



Purchases of dehydrated vegetables for the several Government 

 agencies are inspected by the Fruit and Vegetable Branch of the Food 

 Distribution Administration, United States Department of Agricul- 

 ture. Processing procedures are observed and recorded and the fin- 

 ished product is inspected for quality according to the specifications 

 under which the purchase is made. Certificates are issued only when 

 inspections are made on the sealed containers representing the 

 shipment. 



In order to facilitate inspection and as a direct aid to himself, 

 the manufacturer should follow certain steps. The packaged mate- 

 rial should be coded and warehoused by coded lots. The coding sys- 

 tem used can follow any system desired but should impart the fol- 

 lowing information: Product, type, year, month, day, shift. Thus, 

 if 100 five-gallon cans of julienne potatoes were produced on February 

 1, 1943, on the swing shift, they could be stamped PJ3B1A and ware- 

 housed together as a lot. This code can be stamped on the can, at 

 the time the product is labeled, with a stamp pad and a water-insolu- 

 ble canner's ink. 



Coding entails very little actual expense but yields a great deal of 

 valuable information. It enables the operator to keep an accurate 

 running inventory of his production, and affords a basis for compari- 

 son of the efficiency of personnel and of the yields obtained from dif- 

 ferent lots, varieties, or sources of raw materials. It also enables 

 the operator to find the source of trouble quickly, and affords a means 

 of segregation, without jeopardizing the entire block, in the event 

 that a particular part of the pack fails to meet specifications. In- 

 spections are customarily made on carload lots. 



Samples are drawn at the rate of approximately one container per 

 hundred. The rate may vary according to the number of containers 

 per individual code, the variations within the lots, and other factors. 

 It is the inspector's responsibility to satisfy himself that any given 



