VEGETABLE AND FRUIT DEHYDRATION" 



169 



Table 16.— Dehydration ratios versus coefficients of restoration of iveight of 

 various samples of potato 



[Potato strips ^2-inch thick boiled 10 minutes, with no soaking] 



Item 



Colorado 

 Russet 



Katahdin 



Colorado 

 Pawnee 



Nebraska 

 Triumph 



Water in original sample percent.. 



Water in dry sample do 



Weight of reconstituted sample grams.. 



Ideal weight of reconstituted sample do 



75.5 



7.4 



47.0 



37.5 



124.3 



4.7 



77.5 



5.6 



48.0 



42.0 



114.4 



4.8 



80.6 

 7.1 

 45.0 

 47.9 

 94.0 

 4.5 



85.0 

 6.4 

 49.0 

 62.4 

 78.5 





4.9 







Summary of Rehydration Tests 



It is suggested that the following conditions be met by all who are 

 interested in making rehydration tests : 



Work out a time and temperature sequence suitable to the material being 

 tested. 



Determine the time of soaking and boiling that is compatible with optimum 

 quality in each sample. 



Always run a series of tests at various times and temperatures and evaluate 

 the data on the rate of change in coefficient rather than on a single determination 

 of a coefficient. 



Start the test with at least enough water to submerge the pieces, but do not 

 use so much water that excess amounts are present at the end of the test, 

 especially when quality tests are being made on the samples. 



Shake or stir if necessary to insure wetting of all the pieces during the test. 



Control ther ate of heating so as to prevent rapid and variable losses of water 

 while boiling. 



Use unit heaters set up in such a way as to prevent rise in temperature from 

 radiated or convected heat. 



QUALITY TESTING 



The human reaction to food is defined by four sensory perceptions. 

 The appearance, the feel in the mouth, the taste and flavor, and the odor 

 all contribute to the edibility of the food. Certain characteristics or 

 qualities can be measured quantitatively : Examples are color, size, 

 shape, and in some instances attributes of texture, such as resistance 

 to shearing, breaking, and penetration. Other quality factors are 

 measured by subjective techniques and at best are qualitative in char- 

 acter. Either one of three procedures may be used with more or less 

 confidence in evaluating the purely subjective qualities of a given 

 product. These are described below with certain suggestions as to 

 their value. 



One procedure is to reconstitute a series of samples by a standard 

 method, call in 25 to 30 employees, and ask them which they like best. 

 A refinement of this method is to assign an arbitrary number, let us 

 say 10 for the best sample, 9 for the next best, 8 for the next and so 

 forth, and ask the graders to rate the samples and assign numbers to 

 them. The difficulties in this procedure are obvious. A serious ob- 

 jection is that it may be impossible to achieve. Few if any organiza- 

 tions can assign 25 to 30 employees for y 2 to 1 hour each day for this 

 work. When the make-up of the jury varies from 1 day to the next, 

 the ratings on the samples will vary and nothing is accomplished 

 by the test. Moreover, this method leaves one in ignorance of the 



