HOME DEHYDRATION OF VEGETABLES 



By S. Gilbert Davis, Technical Assistant, William B. Esselen, Jr., Assistant 



Research Professor, and Francis P. Griffiths, Professor, 



Department of Horticultural Manufactures 



INTRODUCTION 



HPHE importance of dehydrated foods to the world at war has been publicized 

 to such an extent that it needs little introduction. In this war one of the 

 major problems is to keep supplies moving to all parts of the world, and among 

 supplies food is always a prime necessity. The ideal way of shipping most foods 

 of which an average of 85 per cent of the fresh weight is water, is in the dehy- 

 drated form. In this form foods weigh from one-fifth to one-twentieth as much 

 as the canned products, and occupy from one-half to one-tenth as much space. 

 The importance of dehydrated foods is not limited to the battle fronts. Indica- 

 tions are that an increase in civilian consumption and production of dehydrated 

 foods is vitally necessary. Vegetable production has been greatly increased by 

 the use of land never before under cultivaticn, in the form of "Victory Gardens" 

 and the like. This factor and the shortage of t-n, steel, and rubber, as well as 

 manufacturing restrictions on home freezers and other types of equipment, 

 emphasizes the necessity for alternate methods of domestic food preservation. 



In considering dehydrated foo:ls it is well to bear in mind that any dehydrated 

 food has undergcne special processing in the course of preparation, and when pre- 

 pared for the table will retain certain characteristics due to such processes. Just 

 as dried prunes, apricots, or raisins are not comparable with the fresh or canned 

 fruits, so it is impossible to compare dehydrated vegetables with the fresh or 

 canned product on the basis of original flavor and appearance. While it is true 

 that most vegetables do not undergo such marked changes in general character- 

 istics as the examples just cited, those changes which do take place should not 

 be judged as deleterious simply because of taste prejudice and the lack of a proper 

 basis for comparison. The quality of different lots of dehydrated foods of the 

 same type can be readily judged and compared. 



Aside from palatability and appearance, the quality of any foodstuff must be 

 judged on the basis of its nutritive value. Unfortunately only meager data are 

 available on the nutritive value of dehydrated foods, although considerable 

 work along this line is in progress in this and other laboratories. In such studies 

 not only the losses in preparation, but the losses under various conditions of 

 storage must be considered. In this respect, the variety of the vegetable may also 

 be of importance. 



NUTRITIVE VALUE OF DEHYDRATED VEGETABLES 



Tressler (1942), in a review of the available literature, found considerable 

 contradictory data, particularly in relation to vitamin retention. This appears 

 to be due, in many instances, to different methods of preparing the products, 

 and in the light of more recent knowledge of preparation methods many of these 

 data are of little value. While comprehensive research is still lacking, from the 

 limited investigations on processing, certain general statements can be made. 



The greatest loss of water-soluble constituents occurs during the blanching 

 process, the loss being greater when water is used as the blanching medium than 

 when the materials are subjected to live steam. Magoon and Culpepper (1924), 



