The olive is a fruit, which grows on
trees and has been cultivated since recorded history. Evidence
suggests it may have originated in Greece and spread to the
countries surrounding the Mediterranean Sea. It stands to reason, as
these countries are the world's major producers of olive and it's
life promoting oils. It was introduced in California and Latin
America sometime in the late 1700's.
The production method of extracting oil
from the olive has not changed much through the centuries. Olives
are harvested by hand and gathered in nets placed on the ground.
They are then taken to mills, which crush the olives into mash
using very heavy stone presses. The intense pressure applied
squeezes the oil and is trapped in large vats. No heat is used in
this "first pressing", thus giving us the liquid in it's purest
form, extra-virgin olive oil. This is the highest grade because it
is less than 1% acid free, which refers to the proportion of free
fatty acids. This first cold pressing accounts for only 1% of all
olive oil produced in the world, making it the most expensive you
can buy. Extra virgin olive oil comes in filtered or unfiltered.
Filtering removes the bits of olive, while unfiltered retains these
bits and appears cloudy at times. Many chefs consider the unfiltered
oil better because of the extra flavor, but it's mostly a matter of
personal taste.
"The Classifications of Olive Oil
Extra virgin olive oil
The purest and highest grade of olive oil, using the choicest
olives, cold pressed, unrefined
and unprocessed to get the
maximum color, taste and aroma. It contains less than 1% free oleic
acid. It is the premium of all olive oils and the most expensive.
Virgin olive oil
Cold pressed oil that comes from a second pressing of pulp of less than top grade olives. It must contain less than 2%
free oleic acid, although it is inferior to extra virgin olive oil,
it still must have perfect aroma, taste and color.
Olive oil
This grade is usually a blend of refined oil using heat and
mechanical processes. It is mixed with virgin olive oil to add color
and taste to it. It may contain up to 3% free oleic acid and costs
less than the virgin olive oil.
Pomace
olive oil
The lowest grade of olive oil. Solvents are used to squeeze whatever
oil is left in the olive mash, after the better grades are
extracted. Like olive oil, taste and aroma is acquired by adding
small amounts of extra virgin olive oil. It is the cheapest of olive
oils, because of it's inferior quality.
Blended olive oil
These are normally a blend of oils using up to 75% canola or
vegetable oil and 25% olive oil to give it some flavor and aroma. It
is inexpensive and is widely used in restaurants and institutions to
cut down costs.
The olive is a fruit, which grows on
trees and has been cultivated since recorded history. Evidence
suggests it may have originated in Greece and spread to the
countries surrounding the Mediterranean Sea. It stands to reason, as
these countries are the world's major producers of olive and it's
life promoting oils. It was introduced in California and Latin
America sometime in the late 1700's. 
The production method of extracting oil
from the olive has not changed much through the centuries. Olives
are harvested by hand and gathered in nets placed on the ground.
They are then taken to mills, which crush the olives into mash
using very heavy stone presses. The intense pressure applied
squeezes the oil and is trapped in large vats. No heat is used in
this "first pressing", thus giving us the liquid in it's purest
form, extra-virgin olive oil. This is the highest
grade because it
is less than 1% acid free, which refers to the proportion of free
fatty acids. This first cold pressing accounts for only 1% of all
olive oil produced in the world, making it the most expensive you
can buy. Extra virgin olive oil comes in filtered or unfiltered.
Filtering removes the bits of olive, while unfiltered retains these
bits and appears cloudy at times. Many chefs consider the unfiltered
oil better because of the extra flavor, but it's mostly a matter of
personal taste.