COMMERCIAL DEHYDRATION ] 1 



dehydration plant. Delays at any point endanger finality. "While 

 vegetables and fruits are held in bins, boxes, or sacks, deteriorative 

 processes set in within their tissues, robbing them of color, flavor, and 

 nutritive values. High temperatures speed up this spoiling. 



Preparation of Products for Dehydration 



The preparation of vegetables and fruits for dehydration is as 

 important as the drying process itself. Speed, cleanliness, and effi- 

 ciency are all-important. Most products are washed ; graded ; peeled; 

 trimmed ; cored. or pitted ; sliced, cubed, shredded, halved, or otherwise 

 divided; washed again; and blanched just before they are dehydrated. 

 These steps are modified for some commodities; onions, for example, 

 are not blanched, and beets are cooked before they are cut. 



In modern food-processing plants most of the preparation processes 

 are performed mechanically. Conveyors move the products. A 

 cylinder equipped with water sprays is commonly used as a washer. 

 Products are mechanically graded into lots of uniform size so that 

 they can be peeled and handled more economically. The essential 

 feature of one type of grader is a vibrating plate with holes of different 

 sizes. Round or approximately round commodities are rolled over 

 slits of increasing width or over revolving rolls spaced at various 

 distances. 



Peeling is done in a number of ways. In the abrasive peeler a re- 

 volving carborundum or rough cement surface grinds off the skins, and 

 running water carries away the scrapings. Hot lye is sometimes used 

 for peeling carrots, potatoes, and sweetpotatoes; the lye is immediately 

 washed off with water. The hot lye treatment also cleans out eyes 

 in white potatoes, thus considerably reducing the labor of trimming. 

 Dipping in hot saturated brine (salt water) loosens the skins of pota- 

 toes and certain other root vegetables so that they can be readily re- 

 moved by vigorous mechanical scrubbing and washing by sprays of 

 water; this method of peeling is being recommended for trial. Scald- 

 ing water loosens the skins of tomatoes, beets, and certain fruits. 

 Flame or radiant-heat peeling may be used for root crops; the intense 

 heat chars the skin, and the char is removed by mechanical brushes and 

 high-pressure water sprays. Some vegetables and fruits are peeled 

 with rotating knives and some by hand. Others do not require peel- 

 ing; cabbage, for example, is trimmed and cored. 



Hand labor is required to a considerable extent for pitting, trim- 

 ming (fig. (j), and final inspection, but dividing, or cutting into pieces, 

 is usually done mechanically. Various types of machines are used 

 for this purpose. The type is not important if the machine is effi- 

 cient in operation, is readilv cleaned, and in conjunction with other 

 equipment maintains a steady and rapid flow of material through the 

 plant. 



Operators must make sure that the products flow steadily and are 

 not allowed to collect in places where they are not kept in motion, 

 since delay may cause spoilage. Equipment and tools and the bins, 

 sacks, and boxes in which the raw products are handled require fre- 

 quent and thorough cleaning. Large quantities of water are required 

 in the preparation of food for processing — as much as 2,000 to 5,000 

 gallons per ton of raw product. An abundant supply of good water, 



