REVIEW SUMMARY 131 



A SUMMARY OF FOOD SUBSTANCES AND THEIR TESTS 



Name 



Chemical Compositiox 



Test 



Starch 



Contains Carbon (C) 



Hydrogen (H) 

 Oxygen (0) 



Solution of iodine turns it dark 

 blue. 



Grape sugar 



Contains Carbon (C) 



Hydrogen (H) 

 Oxygen (0) 



Forms brick-red precipitate 



when heated to boiling with 



Fehling's solution. 

 Forms greenish, yellow, or red 



precipitate when boiled with 



Benedict's solution. 



Fats and oils 



Contain Carbon (C) 



Hydrogen (H) 

 Oxygen (0) 



Leave a grease spot on paper 



after heating. 

 May be extracted by mashing 



up substance with ether. 



Proteins 



Contain Carbon (C) 



Hydrogen (H) 

 Oxygen (0) 

 Nitrogen (N) 

 and usually Sulphur (S) 

 and other elements 



Turn yellow when heated with 

 strong nitric acid, and then 

 turn orange after addition 

 of ammonium hydroxide 



Burning test (odor) 

 Coagulation test (white of egg) 



Mineral matter 



Such elements as Sodium 

 (Na), Calcium (Ca), 

 Iron (Fe), and Potas- 

 sium (K) 



Remains as grayish ash after 

 burning food in hot flame for 

 long period. 



Water 



Hydrogen (H) 

 Oxygen (0) 



Passes off from food when 

 heated, as water vapor, and 

 can be collected on cold 

 metal or glass, as drops of 

 water. • 



Digestion is necessary for plants and animals because : (1) it gives 

 them the nutritious part of their food ; (2) it breaks food into small 

 particles; (3) it releases energy in foods; (4) it makes substances 

 soluble. 



Review Summary 



Test your knowledge of the unit by: (1) Answering and rechecking the 

 survey questions ; (2) performing the assigned exercises ; (3) checking with 

 the teacher, your scores on the various tests, and if you do not have a perfect 

 score trying again the parts you missed ; and finally, (4) making an outline 

 and filling it in as fully as possible for your notebook. 



