PRODUCTION AND UTILIZATION OF FATS AND OILS 7 
soap formed by the action of the caustic soda with the free fatty 
acids clot together into spongy masses. At this stage the tempera- 
ture of the oil is 110° to 120° F. The steam is shut off from the 
heating coils and the agitator is stopped. The oil is allowed to stand 
until the precipitated soap (soap stock) has settled and become firm. 
Then the clear oil is carefully withdrawn from the soap stock and 
run into a tank. If necessary, the oil is washed with warm water to 
remove the last of the soap. At this stage the oil is known as summer 
yellow. 
Large quantities of the summer yellow oil are heated and agitated 
with from 2 to 6 per cent of fuller's earth for a short time and then 
filtered through filter presses, thus becoming bleached. The bleached 
oil is transferred to the high-vacuum deodorizer, where superheated 
steam from perforated pipes at the bottom of the tank is blown 
through until it is practically odorless and tasteless. The deodoriza- 
tion process further bleaches the oil. 
WINTERING 
When cooled to about the temperature of the household refrigera- 
tor, cottonseed oil deposits stearin. To prevent this separation, 
which makes the oil undesirable for use in the home, it is held in 
chilled rooms until the stearin has separated. The olein, or liquid 
portion, of the oil is removed from the solid stearin by pressing or 
by passing the mixture through centrifugal separators. This process 
is known as wintering. A properly wintered oil remains liquid when 
left in the refrigerator. 
Grades 
The following well-defined grades for cottonseed oil have been 
established by the Interstate Cotton Seed Crushers' Association : 2 
CRUDE OIL 
Choice crude cottonseed oil. — Choice crude cottonseed oil must be pressed from 
sound decorticated seed ; must be sweet in flavor and odor, free from water and 
settlings, and must produce when refined as required by these rules, choice sum- 
mer yellow oil at a loss in weight not exceeding 6 per cent. 
Prime crude cottonseed oil. — Prime crude cottonseed oil must be pressed from 
sound decorticated seed, must be sweet in flavor and odor, free from water and 
settlings, and must produce when refined, as required by these rules, prime sum- 
mer yellow oil, with a loss in weight not exceeding 9 per cent, provided that 
any oil that refines with a greater loss than 9 per cent, but still makes prime 
summer yellow oil, shall not be rejected, but shall be reduced in price by a 
corresponding per cent of the contract price of the oil. 
Basis prime crude cottonseed oil. — Crude cottonseed oil shall not be tenderable 
on a basis prime crude contract, if when refined as required by these rules it 
refines to a color darker than 35 yellow and 16 red. 
Off crude cottonseed oil. — Oil neither choice nor prime shall be called off 
oil. When off oil is sold by sample, any oil tendered shall equal sample, but if 
it should refine at a loss exceeding the loss of the sample by not over 5 per cent, 
but otherwise equal, it is still a good tender at a reduced price in proportion 
to the excess loss. The buyer shall have the right to reject any tank of oil 
outright if it tests beyond 5 per cent refining loss as compared with sale sample. 
7 Interstate Cotton Seed Crushers-' Association, rules governing transactions 
between members of the interstate cotton seed crushers' association. p. 7-10. 
[n. p.] 1925. 
