194 American Horticultural Society. 



harder and tougher, and more indigestible, while the sugar, starch, albumen 

 and gluten undergo a slow process of ferment and decomposition. 



None of the starch in the fruit, is converted into sugar, as it should be, and 

 the sugar already existing is, by slow vinous and acetic fermentation, ulti- 

 mately converted into vinegar, so that a sun-dried apple is little else than a 

 spongy piece of hardened cellular tissue filled with dried starch, rotten albu- 

 men and gluten, combined with vinegar, all seasoned with dust, tiy specks 

 and dried insects. 



The changes which take place and the product are the same in all slow 

 processes of drying, either in the sun or kilns, or in some so-called evapora- 

 tors, eycept that the dark color, fermentation and souring, which take place 

 in the sun-dried fruit during the drying, occurs afterwards in that dried in 

 ovens and kilns or slow evaporators 



I will now describe what I call true evaporation. It has been found that by 

 drying fruit rapidly in swift currents of air heated from two hundred to two 

 hundred and forty degrees Fahr. a difterent product is the result, wholly 

 unlike either the fresh or sun-dried fruit, and 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 circu- 

 lation, or the currents are not rapid enough, the fruit will cook and then 

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



Apples will cook in boiling water at a temperature of only two hundred 

 and twelve degrees Fahr., or bake in an oven at two hundred and twenty- 

 five degrees Fahr., but if the heated air circulates fast enough the fruit will 

 not cook or burn or become heated to the temperature of the air which stir- 

 rounds it, for the evaporation of the Avater is a cooling process, and every 

 particle of vapor leaving the minute cells which contained it carries away a 

 large amount of caloric in a latent form, and thus keeps the heat of the fruit 

 far below the surrounding air. 



It is now that the chemical changes belonging to the truly evaporated 

 fruit take place, and the albumen, instead of being slowly dried, is coagu- 

 lated preciselj' as in an egg when boiled. 



The soluble starch existing in all fruit, composed of C,; Hjo <X-, will, if the 

 heat is high enough, combine with one equivalent of water (H. O), so that 

 now we have an entirely different compound, to wit, glucose or fruit sugar, 

 which will assist in the preservation of the fruit, instead of being liable to 

 decomposition as th§ dried starch is in tlie sun-dried and other slow heat 

 products. All the pectine or fruit jelly remains in the cells undecomposed, 

 or is left upon the surface by the evaporation of the water in which it was 

 dissolved, where it may be often seen condensed, instead of passing on with 

 the starch and gluten and glucose into the alcoholic and acetic and finally 

 into the putrefactive fermentation. 



The diastase or saccharine ferment contained in all fruit, and which is the 

 exciting cause of decay, has been rendered inoperative, and all germs of ani- 

 mal or vegetible life have been destroyed by the high heat. 



