THE MANUFACTURE OF FOODS 373 



the potato contains about 18 per cent. However, an acre of 

 land in Europe planted to potatoes can be made to yield a 

 larger amount of starch than an acre of corn. About 50,000,- 

 000 bu. of corn are annually converted into starch and allied 

 products in the United States, which represents, however, but 

 one-fiftieth of the annual production. 



423. Preparation of Corn Starch. The shelled corn is steeped 

 for three or four days in great tanks containing water and sulphur 

 dioxide. This serves to loosen the skin and the germ. The 

 soaked corn is then gently ground in mills which crush the 

 grain, loosening the skin and germ from the part of the grain 

 containing most of the starch. The ground material is then 

 placed in tanks containing water in which the germs float 

 because of the oil which they contain while the starch and skin 

 sink. The germs are dried, ground, and pressed in filter presses, 

 thus removing the oil. Corn oil has many uses as human 

 food. The cake remaining after removal of the oil is called 

 OIL CAKE. It is ground and largely used as stock feed. The 

 starch and skins are re-ground and then put through the 

 shakers which separate the starch from the skins. The 

 skins, or bran, are again ground and again treated to remove 

 the remainder of the starch. The starch suspended in water is 

 then run into long troughs, inclined at a gentle slope. As the 

 starch water flows through the troughs, the starch settles, while 

 the gluten and water flow out at the end of the trough. The 

 gluten is removed from the water, dried, ground, and marketed 

 as GLUTEN MEAL which is used for stock feed. The accumu- 

 lated starch in the troughs is removed, dried, pressed, and 

 made into lump starch. The product still contains from 12 

 to 15 per cent, moisture. 



424. Glucose. Much starch is converted into syrups and 

 sugar known as GLUCOSE SYRUP, or CORN SYRUP, and GRAPE 

 SUGAR. Corn syrup is very extensively used as a food. It 

 is sweet, but less sweet than ordinary sugar. It is without 

 flavor and consequently the table syrups are frequently pre- 

 pared by blending corn syrup and cane sugar, or REFINER'S 



