THE PREPARATION OF CORN OIL. 25 



contain more or less solid glycerids, which settle out when the oil is 

 chilled. In order, therefore, to be sure that an oil will remain clear 

 over the rather wide range of temperatures obtaining in the economy 

 of the ordinary household, the oil must be chilled below the lowest 

 temperatures to which it is likely to be subjected and then filtered. 



SUMMARY. 



The process of preparing an edible oil from crude corn oil con- 

 sists of three distinct operations: (1) Neutralization with caustic; 

 (2) bleaching with fuller's earth; and (3) deodorizing with steam. 



Two methods of refining average corn oil are found to be about 

 equally satisfactory. The soapstock obtained in refining corn oil 

 is soft and slimy, and special means are necessary to harden it. In 

 one of the proposed methods a large excess quantity of caustic is 

 used, while in the other the same result is obtained by adding soda 

 ash after the break. A maximum temperature of 55° C. is recom- 

 mended in the refining of corn oil. 



The value of the chemicals used and the oil lost in the treatment is 

 0.628 cent per pound of neutralized oil with method 1 and 0.564 

 cent with method 2, of which more than 80 per cent is represented 

 by the loss of oil. 



The oil is bleached with fuller's earth according to the method 

 generally used. Not less than 5 per cent of earth must be used. 

 Corn oil does not bleacn as much by this treatment as some of the 

 other vegetable oils. The cost of the materials used and the oil lost 

 in this bleaching process is about 0.22 cent per pound of bleached oil, 

 of which approximately half represents the value of the oil lost. 



The oil is deodorized by being blown with steam for several hours 

 at temperatures above 400° F. under reduced pressure. 



The general arrangement of a refinery equipped to handle two 

 batches of 25,000 pounds of oil a week is described and the passage of 

 the oil through the several processes is discussed. 



The cost of refining corn oil in such a plant as here described is 

 found to be approximately 1.6 cents a pound. This cost figure was 

 obtained by determining as nearly as possible the several charges for 

 chemicals, oil losses, fuel, labor, and overhead. The overhead in- 

 cludes interest on the equipment and depreciation on both equip- 

 ment and building. The value of the equipment, exclusive of the 

 building, is estimated at $40,000. 



