212 MISC. PUBLICATION 5 4 0, U. S. DEPT. OF AGRICULTURE 



Table 28 presents general information on "fruit dehydration by me- 

 chanical methods. Because of the variation in equipment and the fact 

 that fruits are not dried to the low moisture contents of vegetables, 

 except in the form of nuggets and powders, the data vary considerably. 

 As is true of vegetables, the temperature should be carried as high as 

 possible without injury to the product. Experience and the applica- 

 tion of principles discussed' in earlier sections of this manual are 

 necessary in practical operation. 



Table 28.— Prepa 



rition 



and dehydration of fruits x 









Type of piece 



Tray 



loading 



per 



square 

 foot 



Pre treatment 2 



Maxi- 

 mum 

 finish- 

 ing 

 tem- 

 pera- 

 ture 3 



Mois- 

 ture 



content 



of 

 product 



Yield, 

 unpre- 

 pared 

 basis 



Fruit 



Method 



Time 



Apples i _ ._ 



Slices 



Po u n ds 

 1.5 

 2.0 



1. 0-1. 2 

 1.0 

 . 8-1. 

 3.0 

 3.5 

 2.5 

 2.5 

 3.0 



Sulfur... 



Hours 

 Vi-2 

 1-2 



°F. 

 155 

 155 

 150 

 165 

 150 

 160 

 160 

 155 

 150 

 165 



(13) 



Percent 

 15-20 

 15-20 

 10-15 

 24-28 

 5-10 

 15-20 

 15-20 

 15-20 

 10-15 

 15-20 



Percent 

 10-15 



Apricots 5 ... 



Halves 



Whole 



do 



Chopped.. 



Whole 



___-do 



Halves 



.do 



do .... 



15-20 



Berries 6 



15-20 



Cherries (pitted) 7 







15-25 



Cranberries 8 







10-15 



Figs (Kadota) 9 .. 



Sulfur . 



2-3 



25-30 



Grapes 10 .. . .. . 





20-30 



Peaches _. 



Sulfur . 



2-3 

 3-5 



15-20 



Pears u _. . 



do............. 



10-20 



Prunes 12 



Whole 



do 



30-40 



Walnuts . 























i The data presented here were obtained from several sources and represent approximate commercial 

 tunnel-drying practice. Government purchase specifications have been issued for a number of dried fruits 

 and dried-fruit products. 



- If feasible, sulfured fruit is often exposed to sunlight for several hours just before it is dehydrated. 



3 The starting temperature varies with the equipment and the fruit, and can be determined by trial. 



4 Apples are extensively evaporated in kiln driers. (See text.) They are commonly sulfured by immer- 

 sion for 15 to 20 seconds in 0.25 percent sodium bisulfite solution. 



s A somewhat longer sulfuring time is required for sun drying. 



6 Strawberries, raspberries, loganberries, blackberries, and others. 



' Cherries should be dipped in sodium carbonate solution when dried whole. Royal Anne and sour 

 cherries should be sulfured. Unpitted cherries will yield a higher percentage of dried product than that 

 shown in The last column. 



8 Considerable amounts of drum-dried cranberry puree are produced commercially. 



» Figs other thanlvadotas are not sulfured. 



if Light-colored grapes used to produce bleached raisins are dipped in hot lye solution to check the skins 

 and then sulfured about 3 hours. 



11 Longer sulfuring (24 to 48 hours) is used for sun drying. 



12 Hot- or cold-water dip may be used when fruit is to be dehydrated. Lye dip is always necessary when 

 fruit is to be sun-dried. 



13 Not over 110. 



Dried fruits are usually stored in bins holding several tons, if they 

 must be held for some time before delivery to the packer. Packers 

 biry the dried fruits in bulk and grade, process, store, and package 

 them for distribution. Bulk dried fruits are usually handled in boxes. 

 For domestic consumption, dried fruits are usually packaged in paper 

 cartons or in wood or fiber boxes. Fumigation is usually necessary, 

 to destroy insect infestation. Most dried fruits are pressed to some 

 extent when they are packaged. 



APPLES 



Apples constitute about one-fifth of all the fruit grown in the 

 United States. Production is heavily concentrated in Washington, 

 New York ranks second, and a number of other States produce sub- 

 stantial quantities. 



