PEODUCTION AND UTILIZATION OF FATS AXD OILS 13 
OLIVE OIL 
Olive trees are cultivated in the countries bordering on the Medi- 
terranean and in South Africa, Australia, the United States, Mexico, 
and Peru. The oil content of olives depends largely upon the variety 
and upon soil and climatic conditions. Olives cultivated for oil con- 
tain from 30 to 60 per cent. California olives contain from 12 to 
about 30 per cent. Climatic conditions affect the quality of the oil 
so greatly that the olives in a given region may one year produce 
a very fine oil and the next yield one of poor quality. 
California produces about 200.000 gallons of olive oil a year. The 
United States annually imports from 3,000.000 to 6,000,000 gallons 
from Italy, Spain, France. Greece, and Northern Africa. Italy and 
Spain furnish the larger part. 
Preparation 
The methods and equipment employed, both in the extraction and 
subsequent treatment of the oil, vary in different countries. In 
Europe much oil is still made in a very primitive manner, but in 
recent years up-to-date plants have been gradually replacing the 
older mills in the large olive-crushing centers in France, Italy, and 
Spain. In some of these plants centrifugals are employed for the 
separation of the oil from the expressed juice. 
For the production of the finest oil, the olives should be gathered 
just before complete maturity. As most of the olives in California 
are grown for pickling, the cull olives — those that are undersize, 
bruised, or overripe — are chiefly employed in making olive oil. 
These are Trashed, freed from leaves and other foreign substances, 
and crushed, in many of the mills with fluted rollers so adjusted 
that the pits are not broken. 
FIRST PRESSING 
The crushed olives are placed in heavy coarsely woven cloths, 
which are folded to envelop completely each layer or cake of crushed 
fruit. These cakes are piled on top of one another, with wooden 
slats between, until the capacity of the press has been reached. 
Hydraulic presses adapted to the pressing of olives are commonly 
employed, but presses operated by screws or gears are used in some 
plants. During the first pressing the pressure is gradually increased 
to 500 pounds per square inch. 
CLARIFICATION 
The mixture of oil and juice from the presses is transferred to a 
continuous oil washer, and the oil is rapidly separated from the juice 
and larger particles of pulp. The washed oil, rising to the top of 
the washing tank, is drawn off into settling tanks for separating 
the water and any pulp not removed by the washing. By allowing 
the oil to stand a 'month in the first tank and then transferring it to 
a second and later to a third settling tank a perfectly clear oil may 
be obtained. This method of clarifying takes three months or longer. 
In some mills the oil is filtered through filter paper or cotton filters 
until perfectly clear. 
