THE SCIENCE OF THE KITCHEN 107 



4. Effects of disinfectants. 



Mix the white of an egg with about ten times its bulk of 

 water. Pour some of this into each of five test tubes. Allow 

 the first tube to remain as it is ; to the second add a little salt, 

 to tKe third a little sugar, to the fourth sojne vinegar, and to 

 the fifth three drops of formalin. Allow to stand side by side 

 for several days and note any differences in the effect of the 

 substances in preventing decay. 



Preserving foods. Many methods of keeping foods for 

 long periods of time are used ; among the more common are 

 drying, smoking, the use of preservatives, and canning. 

 Drying was one of the earliest methods used and is quite 

 common. Bacteria and molds that cause decay require 

 a certain amount of moisture in order to live and by drying 

 foods the amount of water may be reduced to such a limit 

 that these forms cannot exist. Many foods are already 

 dried as we harvest them, such as the various kinds of grains, 

 peas, beans, and corn; and the food obtained from these 

 by grinding, such as flour and meal, can be safely kept. In 

 other cases artificial drying is used. For some uses even 

 milk is evaporated and reduced to a dry powder that may 

 be kept for a long time. 



Drying fruits and vegetables. Many kinds of vegetables 

 and fruits can be easily dried in the home. This gives an 

 opportunity to save many vegetables that are commonly 

 wasted, either because they are allowed to go to waste in 

 the garden or are left over while preparing meals. 



The general principle involved in drying is that enough 

 water is removed by evaporation so that bacteria and molds 

 cannot live on the product, and it can therefore be stored 

 and kept. The food to be dried is first cut into thin slices, 

 or in the case of corn the kernels are cut from the cob. 

 These may be dried in three ways : in the sun, over a stove 

 or other source of artificial heat, or before an electric fan. 

 For holding the substances shallow trays of any convenient 



