THE PREPARATION OF CORE" OIL. 



11 



oil with practically no unpleasant odor or taste. The details of the 

 process differ somewhat, according to the kind of oil that is being 

 treated. In the case of corn oil the object of the deodorizing process is 

 to remove the peculiar cereal flavor which is so characteristic of the oil. 

 The experiments performed in the deodorization of corn oil were 

 conducted with a view of determining the proper temperature to be 

 maintained and the time of treatment necessary to give the oil the 

 best flavor and at the same time the lightest color. Some preliminary 

 experiments consisted in blowing the previously neutralized and 

 bleached oil with steam under atmospheric pressure. After four or 

 five hours of such treatment the oil when separated from the con- 

 densed steam was found to be entirely odorless, but the color was 

 not improved to any great extent. The oil thus treated was then 

 divided into three lots, two of which were dehydrated and the other 

 kept as a check. Table 5 gives the condition of the three oils after 

 standing in well-filled bottles for some time. 



Table 5. — Effect of the presence of moisture on the keeping quality of deodorized corn oil. 



Sample. 



Treatment for removing 

 moisture. 



• Quality of oil after — 



One week. 



Four weeks. 



Twelve weeks. 



No.l 



None 



Slightly rancid 



Good quality 



do.. 



Distinctly rancid 

 and somewhat 

 musty odor. 



Good quality 



do 





No. 2 

 No. 3 



Heated under vacuum to 95° C. 



for one hour. 

 Stream of carbon dioxid passed 



through the oil for seven hours 



at 70° C 



musty. 



Rancidity becom- 

 ing noticeable. 











It is evident that although steam at ordinary pressure volatilizes 

 the odorous constituents of the corn oil and produces a very accept- 

 able product as regards taste and odor, the oil must subsequently 

 be dehydrated in order to prevent it from rapidly becoming rancid. 



With very few exceptions vegetable oils are deodorized in com- 

 mercial practice by blowing steam through the oil at a temperature 

 of about 200° to 250° C. (392° to 437° F.) under high vacuum for 

 about an hour, the time depending to some extent upon the character 

 of the oil and the type of equipment. The object is to obtain an oil 

 of satisfactory color and taste in the shortest time possible. 



The oil is heated to 200° C. in the deodorizing tank either by direct 

 heat or by means of superheated steam in closed coils placed in the 

 bottom of the tank. Steam is then blown through the oil from a 

 perforated coil. The practice differs with respect to this process, in 

 some cases the steam being superheated. It is evident, however, 

 that the use of superheated steam for this purpose will aid in keeping 



