CARBOHYDRATES I2I 



formed yields alcohol. This, as has been discussed under al- 

 cohol, is the source of most of the industrial alcohol and of the 

 alcohol in both malt and distilled beverages. 



In the animal body two hydrolytic conversions of polysac- 

 charoses occur. First, the digestive process by which starch 

 food is hydrolyzed by the enzyme ptyalin, found in the saliva, 

 and converted into maltose sugar. This is then further hy- 

 drolyzed by the enzyme maltase, found in the saliva and also 

 in the intestinal juice, and yields glucose. Second, the meta- 

 bolic conversion of glycogen in the liver and in the muscle cells 

 into glucose also probably by enzyme action. 



Source of Alcohol. — The industrial processes by which 

 polysaccharoses are hydrolyzed to monosaccharoses, in addi- 

 tion to the natural process of malting grain already referred to, 

 are: First, the hydrolysis of starch by means of boiling dilute 

 acid into glucose for the purpose of obtaining the sugar or 

 sirup known as glucose. Second, the hydrolysis of cellulose 

 by means of acid to obtain glucose which by alcoholic fermen- 

 tation then yields alcohol. This process of obtaining alcohol 

 from cellulose material is being developed at the present time 

 as a means of securing cheap alcohol for industrial purposes. 

 All of these processes of hydrolyzing the polysaccharoses will 

 be considered in detail later in this study in connection with 

 the plants and animals concerned. 



Starch, (C6Hio05)x 



Occurrence and Properties. — Starch is a constituent of some 

 part of practically all plants. It occurs in especially large 

 amounts in such plants as potato tubers, wheat, corn and other 

 cereal grains, arrowroot, certain palms (sago), cassava, etc. 

 In its general properties and relation to water, starch belongs 

 to the class of bodies known as colloids. It does not dissolve 

 in water, but may be so mixed w^ith it as to remain suspended 

 indefinitely in the form of an emulsion. In such form it is 

 known as starch paste. It is non-diffusible through a semi- 

 permeable membrane. When dry, starch is a fine powder and 



