VEGETABLE AND FRUIT DEHYDRATION 21 



mate these requirements. For the storage of root crops, such as 

 potatoes and carrots, in the cool fall months nothing more than a 

 covered shed may be needed. The special requirements of each crop 

 are discussed in a later section of this publication and these, together 

 with commercial experience in the district, should be consulted to 

 determine whether or not unrefrigerated storage will suffice. Plans 

 for farm storage plants that use outside air to maintain temperatures 

 can be obtained from the United States Department of Agriculture, 

 Washington, D. C. 



If refrigeration is needed, the kind of plant that is installed will 

 be determined by the availability of equipment and the investment 

 warranted. Storages refrigerated by ice bunkers and fans instead of 

 mechanical refrigeration have been constructed in recent years for 

 crops that have a short season, such as stone fruits and grapes. The 

 initial investment is lower than for mechanically refrigerated plants 

 and desirable humidities of 85 to 90 percent are easy to maintain. 

 Combination ice-bunker and mechanically refrigerated plants have 

 been constructed that utilize the high refrigeration capacity of ice 

 bunkers to cool the commodity and a small compressor to maintain 

 temperatures during storage. The more common type is the storage 

 plant refrigerated entirely by mechanical refrigeration, and it may 

 be one of several designs. 



Whatever the type of plant installed, it should have refrigeration 

 capacity sufficient to cool the produce to within a few degrees of the 

 recommended storage temperature in 18 to 24 hours, and it should 

 maintain temperatures throughout the rooms within a degree or two 

 of the specified temperature. The correct humidity should also be 

 maintained within 2 or 3 percent. These specifications if insisted 

 upon will insure ample refrigeration capacity, good air volume and 

 distribution, and suitable air-temperature control. The lay-out of the 

 plant for convenience in loading and unloading will likewise be an 

 important matter to discuss with the engineer designing the plant. 



Transportation 



If the dehydration plant is located close to the area of production, 

 as it should be, there will be few transportation problems. Generally 

 the methods found adequate for the trucking or carlot shipment of 

 produce for the fresh market should suffice for the dehydrator. When 

 perishable crops, such as spinach, asparagus, peas, and sweet corn, 

 are to be in transit for 10 or 12 hours or longer, icing the container 

 or the load with crushed ice will help to preserve quality and nutri- 

 tive value. This may be advantageous for even shorter hauls. 



String beans, which are often harmed by wetting, may be benefited 

 by precooling in cold air before shipment. For products that are 

 shipped some distance, refrigerated trucks or refrigerator cars will 

 be needed. The refrigerator car lines serving the district can be 

 consulted as to the refrigeration services in general use for specific 

 commodities. A new type of car, equipped with fans to circulate air 

 in transit, is available in limited quantities in some districts. These 

 provide better refrigeration in transit than standard cars, and will 

 be found especially adaptable to perishable commodities that are 

 shipped without top icing the load. 



