392 



GENERAL SCIENCE 



Corn 



i.e., indigestible. It is needed, however, to give bulk to 

 foods. Glycogen is the form in which carbohydrates 

 are normally found after absorption in the liver and 

 muscles. 



Glucoses. Common representatives of this group 

 of carbohydrates are known as dextrose or grape sugar, 

 levulose or fruit sugar, and galactose. Invert sugar is 



a mixture of equal parts 

 of dextrose and levulose. 

 There is no essential dif- 

 ference in these com- 

 pounds except in their 

 effect on polarized light. 

 Dextrose in solution has 

 a right-hand rotary effect 

 on polarized light ; levu- 

 lose, a left-hand effect ; 

 and galactose, a right- 

 hand effect. 



Dextrose is found in 

 ripe fruits and vegetables, 

 in corn sirup, in the digestive tract as the result of the 

 action of the digestive juices on sugars and starches, and 

 in cooked fruits, due to the action of the fruit acids on the 

 sugar used for sweetening. It is less sweet than sugar 

 and gives a reddish color when tested with Fehling's 

 solution. 



Levulose is found as a companion of dextrose. It is 

 much sweeter than dextrose and does not crystallize 

 readily. It gives the same test as dextrose with Feh- 

 ling's solution. 



Fehling's solution test. Prepare Fehling's solution 

 by dissolving 6.2 grams of copper sulphate, 3.5 grams of 



Pa ' 

 Wheat 



Bean 



FIG. 350. Starch Grains from Various 

 Foods. 



