The olive tree boasts two prizes—the olive itself (called the table olive) and the precious oil pressed from the fruit's flesh. In fact, a third prize is the tree which has a twisted trunk full of character, grey-green leaves, and wood which can be used for carving and furniture-making. Fallen fruit looks edible, but it isn't. All olives, whether green or black, require processing before they can be eaten.


The olive tree has been given the Latin name Olea europaea and is from the botanical family called Oleaceae. It is an evergreen that typically grows from 10-40 ft (3-12 m) tall. The branches are fine and many, and the leathery leaves are spear-shaped and dark green on their tops and silver on their undersides.

The trees bloom in the late spring and produce clusters of small, white flowers. Olives grow erratically (unless the trees are cultivated and irrigated) and tend to either produce in alternate years or bear heavy crops and light ones alternately. Seedlings do not produce the best trees. Instead, seedlings are grafted to existing tree trunks or trees are grown from cuttings. Olives are first seen on trees within eight years, but the trees must grow for 15-20 years before they produce worthwhile crops, which they will do until they are about 80 years old. Once established, the trees are enduring and will live for several hundred years.

Olives mature on the tree and can be harvested for green table olives when the fruit is immature or left on the tree to ripen. The ripe olives are also harvested for processing as food but are left on the trees still longer if they are to be used for oil. Six to eight months after the flowers bloomed, the fruit will reach its greatest weight; and 20-30% of that weight (excluding the pit) is oil. Inside each olive, the pit contains one or two seeds; botanists call this kind of fruit with a seed-bearing stone a drupe; plums and peaches are other drupes.

Olives grow in subtropical climates in both the northern and southern hemispheres. Hundreds of varieties are grown; some produce only table olives, and others are cultivated for olive oil. Italy and Spain lead world production of olives; and Greece, Morocco, Tunisia, Portugal, Syria, and Turkey also consider the olive an important part of their economies. Europe produces three-fourths of the world's olives and also leads in consumption of both table olives and olive oil. California has also become a respected producer, especially since the health benefits of the olive have been widely recognized.


Cultivation of the olive is as old as the civilizations that encircle the Mediterranean Sea. The indications that people had learned the secrets to making olives edible date from the isle of Crete in about 3,500 B.C. The Egyptians recorded their knowledge of the olive around 1,000 B.C. , and the Phoenicians exported it to Greece, Libya, and Carthage. The Greeks further carried the olive to Sicily, Southern Italy, and Spain. The Romans also mastered olive cultivation. Around 600 B.C. , they had a merchant marine and stock market just for the oil trade. Sardinia and the south of France became olive-growing regions, thanks to the Romans.

Olive branches, leaves, and wood gained sacred connotations in both Testaments of the Bible, like the dove's return to Noah's Ark with an olive leaf in its beak. In the Olympic Games in Greece, the victors were awarded crowns of olive branches and leaves. Oil figured in the anointing of athletes, rulers, and religious authorities and was used as lamp oil by most ancient civilizations on the Mediterranean rim. It was olive oil that burned on empty for eight days in the Hebrews' eternal flame during the miracle celebrated as Hanukkah. The olive's fragrant wood was reserved exclusively for altars to the gods, and all of these uses helped make the olive a symbol of peace.

In the 1500s, Spanish missionaries brought the both the grape and the olive to California. In South America, Italian immigrants planted the olive, and they were also responsible for plantings in Australia and southern Africa. The olive achieved new fame in California when, in 1870, an inventive bartender added the fruit to a new concoction named the Martinez for the town he lived in; the olive-ornamented cocktail is known today as the martini.

Raw Materials

The olives themselves are the most important raw material. Depending on the curing method, pure water, caustic soda or lye, and coarse salt are used. Flavorings can be added to the brine. Among the favorites are red pepper or a variety of Mediterranean herbs for black olives and lemon or hot green peppers or chilies for green olives. Fennel, wine vinegar, or garlic can be used to add interest to any olive, but the time required for the olives to take on these flavors can range from a week for whole chilies to several months for a more subtle taste like the herb fennel.

Pitted green olives can be stuffed to add color, flavor, and texture. Almonds, pearl onions, sliced pimentos, mushrooms, anchovies, and pimento paste are the most common olive accessories.


"Design" of olives includes variety, color with green or ripe olives as the two basic differences, and method of curing. Kalamata olives from Greece are one of the best-known varieties and are distinguished by their purplish brown color and elongated shape with a sharp point. The green Manzanilla is the most famous Spanish olive and is now also cultivated in California. The Nicoise olive from France is famous for the tuna salad that requires the olive as an ingredient. Naturally cured olives can vary in color from a wonderful range of greens to purple, black, brown, and even the small Souri olive from Israel that is brownish pink.

The key to the flavor, color, and texture of the olive is the moment of harvest. Obviously, the fruit can be harvested when it is green and unripe, fully ripened to black or any stage in between. Older fruit can be salt-cured or dry cured to produce a salty, wrinkled product. Damaged fruit can still be used by pressing it into oil. It is the combination of the harvest, the cure, and any added flavors that yield the characteristics sought by the producer and consumer.

Until recently, most olives available in American grocery stores were artificially cured, meaning that they were treated with lye to remove their bitterness. This is still true for all canned black olives, many of the green olives imported from Spain and the black Nicoise from France, and other bottled versions; however, renewed appreciation of the olive has led to interest in naturally cured olives that are now generally available at deli counters and are bottled by some specialized manufacturers. Naturally cured olives are cured with either oil or brine and additives like wine vinegar for flavor.

Lye treatment is done to remove the bitterness of the olive. Olives contain oleuropein (after their botanical name Olea europea), and it is this substance (a compound called a glucoside) that makes them too bitter to eat directly from the tree. According to the purists, lye-cured olives are bland, either spongy or hard (but not crunchy), with most of the flavor gone. Lye-cured olives are also almost always pitted, and the most naturally flavorful part of the olive is adjacent to the pit. Curing with lye softens the olive so it can be picked when it is still hard, but olives to be naturally cured must be more ripe, handled carefully, and processed quickly.

In order to produce edible olives, harvested olives are cleaned and then cured in a natural brine of salt, oil, and flavorings or artificially with lye. For green olives, the salinity is increased by 2% every two to three weeks from the initial salinity of 12-14%. Black olives begin their curing at 8-9% salinity; this is increased by 1-2% every two weeks until a maximum solution of 22-24% is reached. Taste of the final product depends upon variety, time of harvest, and curing solution.

The Manufacturing

In the field

In the processing plant

Other curing and canning methods

Quality Control

The quality of olive processing is protected by many sets of hands and eyes. Steps from hand-picking in the grove to hand-culling of olives on the shaker table are monitored by touch. All other processes are watched carefully. Chemistry is regulated by relatively simple instruments, and taste tests help assure the crunch of cured olives and the blending of flavors.


Olive producers usually manufacture olive oil as well. Another byproduct that is growing in popularity is processed olive leaves. They are made into tea, put in caplets as crushed leaves, and processed as an extract or in tablets; all forms are believed to aid blood flow and inhibit viruses and diabetes.

Waste from olive processing consists of the pits and damaged fruit. The pits are sold as food for pigs, and all other olive waste can be ground and used as organic fertilizer. Some manufacturers return it to their groves to fertilize the olive trees.

The Future

A ripe future is predicted for the olive business thanks to three occurrences. Medical studies have shown that olives and olive oil are healthful foods that provide vitamins, minerals, and other nutrients. They may reduce the risk of heart attacks and breast cancer, among other diseases. In America, the influence of immigrants from Spain, Italy, and the North Coast of Africa who are accustomed to naturally cured fruit has led to an interest in flavorful olives; specialty growers are reaching this market with carefully crafted, flavored olives. Finally, the "discovery" of crunchy, tasty, nutritious, naturally cured olives by a growing public is leading to the decline of canned ripe olives, which may disappear from the marketplace by about 2010.

Where to Learn More


Klein, Maggie Blyth. The Feast of the Olive. San Francisco: Chronicle Books, 1994.

Rosenblum, Mort. Olives: The Life and Lore of a Noble Fruit. New York: North Point Press, 1996.


Clark, Melissa. "An Ode to the Olive." Vegetarian Times (October 1997): 136.

Hamblin, Dora Jane. "To Italy, Olive Oil is Green Gold." Smithsonian (March 1985): 98.

Johnson, Elaine. "Know Your Olive Options." Sunset (April 1995): 164.

Kummer, Corby. "Real Olives: In Praise of an Old World Treat, Pits and All." The Atlantic (June 1993): 115.

Wing, Lucy. "A Taste of Olives." Country Living (September 1994): 142.


Australian Olive Association http://www.australianolives.com.au/ .

Australian Olive Association and Information Center. http://pom44.ucdavis.edu/olive2.html/ .

Naomi's Olive Page, "An Ode to the Olive" http://www.bayarea.net/-emerald/olive.html/ .

The Olive Oil Source. http://www.oliveoilsource.com/ .

Santa Barbara Olive Company. Http://www.sbolive.com/ .

Gillian S. Holmes

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Apr 17, 2009 @ 11:11 am
I have a small orchard of olive trees and need to know what to do with the fruit and how. Thanks for any help.
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Jan 11, 2011 @ 9:21 pm
I'm curious how the olives are pitted and stuffed. Is there any way to see the process on
