UNITED STATES DEPARTMENT OF AGRICULTURE 



DEPARTMENT BULLETIN No. 1141 



Washingtcn, D. C. 



May, 1923 



EVAPORATION OF FRUITS. 1 



By Joseph S. Caldwell, Plant Physiologist, Office of Horticultural and Porno- 

 logical Investigations, Bureau of Plant Industry. 



CONTENTS. 



Page. 

 Extent and character of the fruit- 

 drying industry 1 



Principles involved in drying fruits_ 4 



Community drying plants 7 



Buildings and equipment for drying- 8 



The kiln evaporator 8 



The individual kiln 9 



The kiln drying plant 15 



The apple-drying workroom and 



its equipment 17 



The prune tunnel evaporator 24 



The operation of the tunnel 



evaporator 27 



Small driers or evaporators 85 



Treatment of the various fruits 35 



Apples 35 



Page. 

 Treatment of the various fruits — Con. 



Peaches : ^5 



Apricots 49 



Pears 49 



Cherries 50 



Prunes 50 



Small fruits 54 



Storing the dried products 57 



Preparing evaporated fruits for 



market 58 



Packing evaporated apples 58 



Packing peaches, apricots, and 



pears 50 



Packing prunes 61 



Laws relating to evaporated and 



dried fruits 62 



EXTENT AND CHARACTER OF THE FRUIT-DRYING 



INDUSTRY. 



THE TERMS " dried fruit " and " evaporated fruit " are popu- 

 larly used to designate all fruits preserved by reduction of their 

 moisture content to such a point that spoilage does not occur. In the 

 trade the term " dried fruit " is applied to any product in which mois- 

 ture reduction has been brought about by exposure of the fresh mate- 

 rial to the heat of the sun. while products made by driving off the 

 surplus moisture by the use of artificial heat are known as " evapo- 

 rated " fruits, less frequently as dehydrated or desiccated fruits. 

 While the processes of sun drying and drying with artificial heat 

 in evaporating devices are widely different, the differences in the 



1 This bulletin is of interest to fruit growers who have such qxiantities of surplus fruit 

 to require the employment of large-scale factory methods for its utilization. It is 

 intended to serve as a rather complete nontechnical handbook of information in regard 

 to methods of evaporating fruits which are applicable to farm conditions. 



This bulletin supersedes Farmers' Bulletin 903, "'Commercial Evaporation and Drying 

 , Fruits. ' by James II. P.eattie and II. I'. Gould. Much of the material in that publica- 

 tion is reproduced, with revision, in this bulletin. New sections dealing in considerable 

 detail with the construction of the driers, the arrangement of the equipment, the practical 



tails of handling the various fruits, and the choice of fruits to be used for evaporating 

 purposes have been edded. 



25407°— T, 



