Page 6 



BETTER FRUIT 



September, rprp 



Dehydration as a Factor in the Fruit and Food World 



By W. H. Walton, Editor Better Fruit 



Uet-eiving loganberries lur (ieh>dratiun at 



Salem, 



THE preservation of food by drying 

 has been in use for centuries and is 

 probably the oldest known method 

 which the human race has employed in 

 food conservation. The process em- 

 ployed by the ancients and which is 

 still largely employed is to place the 

 fresh food, more particularly cereals 

 and fruits, in the sun and allow the rays 

 of this great heat and light-giving orb 

 to gradually eliminate the moisture. In 

 semi-arid sections where continuous 

 sunlight can be depended upon over a 

 considerable period this method of dry- 

 ing food is a success, with the exception 

 that the food spread on trays out of 

 doors is a prey to the insects and gath- 

 ers considerable dirt, due to sudden 

 gusts of wind and the dust particles that 

 are in the air at all times during the dry 

 season. These handicaps are no small 

 objection to sun-dried food, in addition 

 to the fact that some fruits and vegeta- 

 bles do not ripen until the rainy season 

 sets in and puts an end to drying food 

 by nature's process. 



To meet the growing demands for 

 dried fruits, such as apples, apricots, 

 prunes, pears and some of the other 

 tree fruits, evaporating machines were 

 evolved, and, while they proved a suc- 

 cess, failed to be adapted to the needs 

 of the entire fruit, vegetable and other 

 food kingdoms. It was this need that 

 caused the birth of dehydration, which, 

 reduced to its simplest terms, means 

 merely the extraction of water, or the 

 elements of water. "Dehydration," an 

 expert on this subject says, "has come 

 as a term to distinguish a special type 

 of process to preserve fruits, vegetables, 

 meats, fish and eggs for indefinite per- 

 iods. Properly done, this process entails 

 no loss of the original constituents ol 

 the material. The mineral salts, vita- 

 mines, acids, proteins, etc., are retained 

 in their original fullness and the cellu- 

 lar structure remains intact. 



the plant of the King's Products Company, 

 Oregon. 



The first experiments in drying foods 

 according to this principle were not 

 altogether a success, as the method of 

 drying was accomplished by either a 

 horizontal air wave passing over or a 

 vertical wave passing through the mate- 

 rial. Circulation was obtained by means 

 of drafts and the natural rising of 

 heated air. The temperatures during 

 this process ran from 140 to 190 degrees 

 and subjected the material to such an 

 intense heat that its entire content was 

 often made valueless. The basic prin- 

 ciple of the new process of dehydration 

 is a gradual extraction of the moisture 

 content by means of low temperatures. 



The material to be dehydrated is 

 spread on shallow trays, which are slid 

 into steel cars, and the cars then rolled 

 into long, tightly sealed tunnels. The 



I)rocess that takes place is similar to 

 that of a warm arid wind. The tem- 

 peratures are kept low, but the volume 

 of air jiassing through the tunnels is 

 rapid, varying from 25 to 50 feet per 

 minute. Circulation is artificially cre- 

 ated by fans, and the air is used but 

 once, preventing the carrying of the 

 odors and moisture from one tray to 

 another. The moisture is removed so 

 gradually that the cell structure of the 

 materials remains intact, the flavor un- 

 injured and the food value unimpaired. 

 The retaining of the cell structure is 

 probably the most important feature of 

 this process, on account of the fact that 

 when the finished product is placed in 

 water it will reabsorb the original 

 amount of moisture it contained, largely 

 regaining in this way its fresh color and 

 flavor and the wholesome, nourishing 

 properties of the freshly gathered pro- 

 duce. In showing how greatly the 

 weight of the fresh material is reduced 

 when dehydrated the following table 

 will be of interest: 



NUMBER OF POUNDS OF FRESH MATERIAL 



REQUIRED TO MAKE ONE POUND 



OF DEHYDRATED. 



Apples 10 



Apricots 5 



Cherries (pitted) 5 



Loganberries 6 



Pears (peeled) 8 



Peaches (peeled) 10 



Prunes 3 



Raspberries 6 



Strawberries 8 



Cranberries 6% 



Beets 9 



Stringless Beans 10 



Cabbage 12 



Carrots 10 



Celery 20 



Onions 10 



Parsnips 8 



Potatoes 6 



Pumpkin 13 



Rhubarb 20 



Squash 9 



Spinach 15 



Tomatoes 15 



Turnips 15 



While the great economic value of 

 artificial dehydration had been realized 



Spreading loganberries on trays preparatory lo being dehydrated. To the right can be seen the 

 partially loaded steel cai-s which are used in roviting the food materials through the plant. 



