16 BULLETIN 1054, IT. S. DEPARTMENT OF AGRICULTURE. 



and rank all four of them as better than the solvent oils from the 

 cake. 



After these opinions had been received the oils were again tested 

 in the laboratory, and it was found that some deterioration had 

 taken place in some of the oils during the five weeks which had 

 elapsed since they were deodorized. The bottles containing the oils 

 were not quite full and were kept during the interval in a dark 

 place. The changes noted were greatest in the oils from the oil 

 cake and possibly slightly greater in the benzol-extracted oils than 

 in the expeller oils. There seems little doubt that the general quality 

 of these oils could have been materially improved with a more 

 thorough deodorization. The deodorization of oils in the laboratory 

 on a small scale has certain limitations and can not quite compare 

 with commercial operations. The vacuum obtainable in these ex- 

 periments was not as great as desired, and the arrangement used 

 for raising the oil to the proper temperature might have led to 

 unequal heating. It is probable that a more thorough deodoriza- 

 tion would not only improve the quality of these oils but would pre- 

 vent them from deteriorating rapidly on standing. 



SUMMARY. 



Corn oils obtained by means of expellers and by benzol extraction 

 from comparable samples of both dry-process and wet-process corn 

 germs and oils obtained by benzol extraction from the expeller cake 

 were compared as to character and quality. 



Of the crude oils those extracted from the cake were the darkest 

 and deposited the greatest amount of sediment on standing. The 

 benzol-extracted oils from the wet-process germs contained more free 

 acids than the oils obtained by that method from the dry-process 

 germs, this being especially true of the oils from the cake. All the 

 oils were refined in the same manner, with the exception of the benzol- 

 extracted oil from the dry-process germ cake. Owing to the sediment 

 present, this oil required a greater quantity of caustic. The oils were 

 all deodorized by blowing them with a current of steam at 225° C. 

 (437° F.) for two hours under a vacuum of 25 inches. This treat- 

 ment removes odorous volatile constituents and in the case of solvent- 

 extracted oils tends to remove the final traces of the solvent. 



The expeller oils showed the lowest loss on treatment with caustic ; 

 in the oils obtained by benzol extraction from the germs the loss 

 was somewhat greater, and the benzol-extracted oils from the oil 

 cakes showed by far the greatest loss. 



There were no striking differences in the physical and chemical 

 constants of the oils either with respect to the two types of germs 

 from which they were produced or to the method of production. 



