COKX OILS. 
Table 4. — Percentage of free fatty acids in crude com oils. 
11 
Oils. 
Percentage 
of free 
fatty acids. 
Oils. 
Percentage 
of free 
fatty acids. 
Sample A, wet-process germs by ex- 
1.76 
2.15 
3.60 
Sample D, dry- process germs by ex- 
1.72 
Sample B, wet-process germs by sol- 
Sample E, dry- process germs by sol- 
1.90 
Sample C, wet-process oil cake by sol- 
Sample F, dry-process oil cake by sol- 
vent 
1.88 
It is of interest to note that the oils from the dry-process germs 
(D. E. and F) are uniformly lower in free fatty acids than the oils 
from the wet-process germs. There appears to be practically no 
difference between the free acidity of the benzol-extracted oils and 
the expeller oil of this group. In the case of the oils from the wet- 
process germs (A, B, and C), the benzol-extracted oils contain more 
free fatty acids than the expeller oil. This is especially true of the 
oil extracted from the oil cake (C). 
REFINING 2 THE OILS. 
The six foregoing oils were refined as nearly alike as their indi- 
vidual character would permit. The bleaching and deodorizing 
were done in the same way in the case of each oil, but the method 
of neutralizing with caustic required some modifications with cer- 
tain of the oils. It was the intention to treat all as nearly alike as 
possible, so that whatever differences might be noted in their quality 
after refining could logically be assumed to be due to the inherent 
differences in the oils obtained by the two methods of removal from 
the germ. 
NEUTRALIZATION WITH CAUSTIC. 
After a number of preliminary experiments it was found that the 
method of neutralizing the oils with caustic described in a previous 
publication (44) seemed likely to give the most generally satisfactory 
results on the oils as a whole. After the preliminary experiment, 
5-pound batches of oil were used in each case. The method used was 
as follows: 
To the cold oil there was added slowly, while stirring, sufficient 14° BS. 
sodium hydroxid to neutralize the free fatty acids present plus 50 per cent 
excess. After being stirred for 10 minutes the oil was slowly heated while the 
stirring was continued and the temperature raised to 55° C, until the oil 
broke. After the break 2 per cent of powdered soda ash was added gradually 
and the stirring continued for 5 minutes longer. The oil was then kept for 
3 hours at a temperature of 50° C, after which it was allowed to cool over 
night and then drawn off from the deposited soap stock. Channels were cut 
2 The term " refining " as here used includes the three main operations usually em- 
ployed in making edible oils: (1) Neutralization with caustic, (2) bleaching with 
fuller's earth, and (3) deodorizing with steam. 
