I 



INDUSTRIAL USES OF PLANTS 397 



here. In Europe, large amounts of starch are extracted from 

 potatoes, which are used also but to a much lesser extent for that 

 purpose in the United States. Wheat and rice are of minor 

 importance as starch producers, as are several tropical plants, 

 the sago palm, arrowroot, and cassava. In all cases the starch is 

 extracted from the plant tissues by first grinding to break down 

 the cellular structure and free the starch grains, and then washing 

 with a slow running stream of water which washes out the insolu- 

 ble grains. They are allowed to settle out and are then dried in 

 kilns after which the starch is ready for the market. 



There are a number of products manufactured from the freed 

 starch grains which are important industrially. One of these is 

 DEXTRIN, a tasteless white solid with high adhesive qualities, 

 which is widely used as a substitute for the natural gums. Corn- 

 starch dextrin is the adhesive which coats the backs of United 

 States postage stamps. Dextrins are also used for glazing papers 

 and cards, and in the textile industry as an aid in dyeing cloths. 

 These substances are obtained by treating starch with dilute 

 acids often accompanied by heat, or enzymes which decompose 

 starch into dextrins. 



If this decomposition is carried far enough, starch is com- 

 pletely broken down into glucose, a simple sugar. In the United 

 States this is manufactured from cornstarch, and often referred 

 to as corn syrup. It is widely used as an infant and invalid food, 

 since it is a sugar in its most simple and available form, and for 

 candy making, cooking, and sweetening purposes in general. 



When the insoluble starch grains are heated in water, they 

 swell and burst, forming a paste-like substance known as soluble 

 starch which is widely used for giving a "finish" to textiles and 

 papers in their manufacture, and in laundry work as a stiffening 

 agent to keep the ironed clothes fresh and free from wrinkles. 



Large quantities of industrial alcohol are manufactured 

 from starch by first converting it into sugar by action of the 

 enzyme diastase, and then converting the sugar into alcohol by 

 fermentation with yeasts. This alcohol is known as ethyl, or grain 

 alcohol, and is used in the manufacture of many other products, 

 as well as being widely used as a solvent and anti-freeze for 

 automobile radiators. For all these uses the alcohol is "denatured" 



