CHAPTER VII 

 SELECTION AND PREPARATION OF FOODS 



Foods. The development of energy in the body de- 

 pends upon its fuel or food supply. When the food 

 supply gets low, the need of the tissues for more food 

 causes an increasing discomfort until we satisfy our 

 hunger. Those substances which "satisfy hunger by 

 furnishing the energy necessary for the various activi- 

 ties of the body, and which are also wholesome in all 

 their effects when taken in moderate amounts, are foods. 

 The foods which animals need for their growth and ac- 

 tivity are manufactured by plants from the simple sub- 

 stances furnished by the air, water and soil. After the 

 plants have built them into their own complex tissues, 

 they are found to be of three principal kinds, namely, 

 carbohydrates, hydrocarbons and proteids. 



Carbohydrates. To the first group belong cellulose, 

 starch and sugar, which are found in varying amounts 

 in most vegetable tissues and furnish the main food 

 of the majority of animals. They consist of carbon, 

 hydrogen and oxygen in a number of different propor- 

 tions. 1 Since they all have twice as much hydrogen 

 as oxygen, they are in the right ratio to form water 

 (H a O), and for this reason they are called carbohy- 

 drates (literally, carbon watered). 



Hydrocarbons. The second class is represented by 

 the oils obtained from nuts and from the palm, olive, 



1 Starches (gums and cellulose), C 6 H,,O 5 . 

 Sugars (grape sugar, glucose, etc.), CaHi 2 O 6 . 



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