CARBOHYDRATES 125 



Inulin 



Inulin is another starch-like carbohydrate found in certain 

 plants, e.g. in potatoes, dandelion roots and dahlia tubers. 

 On hydrolysis inulin is converted into fructose alone and not 

 glucose. 



Cellulose 



Cellulose is one of the most important carbohydrates, con- 

 sidering its wide distribution in nature and the useful prod- 

 ucts made from it. The other two most important carbo- 

 hydrates considered in this same way are cane sugar and starch. 

 Cellulose is as widely distributed in nature as starch, and is the 

 chief constituent of the fibrous portions of all plants. The 

 fiber of cotton, flax and hemp plants is nearly pure cellulose 

 and yields the materials known as cotton, linen and hemp, 

 from which important products are made in the shape of cot- 

 ton wool, thread or cloth, linen thread or cloth, and hempen 

 twine and rope. It occurs also as the fibrous constituent of 

 the straw of cereal grains and grasses, and in trees. 



In woody fibers of the latter cellulose is not pure, but is 

 present together with (probably in combination with) other 

 substances known as lignin, cutin, etc., the compounds being 

 termed ligno-celluloses in the first case and adipo-celluloses in 

 the latter. In juicy fruits and also in the stems and roots of 

 plants the cellulose or fibrous part contains similarly com- 

 pounds of cellulose with another group of substances known as 

 pectins, the compounds being termed pecto-celluloses. When 

 fruit juices form jellies, it is due to the decomposition of these 

 pecto-celluloses and the gelatinization of the pectins resulting. 



Cellulose, like starch and unlike sugars, is insoluble in water, 

 and unlike starch does not go into solution or colloidal suspen- 

 sion on boiling. When heated with dilute sulphuric acid, cellu- 

 lose is converted into a starch-like substance called amyloid 

 which gives the starch blue test with iodine. When this is 

 boiled with acid it is hydrolyzed to glucose. Thus cellulose may 

 be converted into glucose which may later be fermented to alco- 



