STORING, PRESERVING, ETC. 91 



I am acquainted -with, for which I am indebted to an 

 eminent American scientist, Dr. J. F. Symons, of Fayette- 

 ville, Arkansas. It is the account he gave to the ' South- 

 West Association of Fruit and Vegetable Evaporators' 

 at Springfield, Mo., and will, I hope, afford useful infor- 

 mation as to the reasons why properly evaporated fruits 

 are superior to those which are sun-dried or kiln- dried. 

 Dr. Symons says : 



" ' I will no\v describe the process of true evaporation. 

 It has been found that by removing a part of the water 

 rapidly, in swift-moving currents of air, heated from 240 

 F., a different product is the result, wholly unlike either 

 the fresh or sun-dried fruit, which will keep better, is 

 more digestible and nutritious, is less acid, and will sell 

 for more in the market. But if, after having heated the 

 air hot enough, there is not sufficient circulation, or the 

 currents are not rapid enough, the fruit will cook and 

 then dry, or burn the same as in a close oven. Appier 

 will cook in boiling water at a temperature of only 212 

 F., or bake in an oven at 225 F. ; but if the heated air 

 circulates fast enough, the fruit will not cook or burn or 

 become itself heated to the temperature indicated by the 

 thermometer, even at 300 F., for the evaporation of the 

 water is a cooling process, and every particle of vapour 

 leaving the minute cells which contained it carries with 

 it also a large amount of caloric in a latent form, and 

 thus keeps the heat of the apples far below the surround- 

 ing air. The chemical changes which belong to truly 

 evaporated fruit will now begin, and the albumen, instead 

 of being slowly dried, is coagulated precisely the same as 

 in an egg when boiled. The soluble starch existing in all 

 the fruit, and composed of C C H 10 5 , will, if the heat is 

 high enough, combine with one equivalent of water 



