Introduction to Olive
Olive, a family of trees and shrubs. The common olive tree, the subject of this article, is the plant of most economic value in this family. Its fruit, a source of vitamins and of protein, is eaten as a snack or appetizer and in salads, sandwich fillings, sauces, and casseroles. It is also a source of oil. The fruit's pits and pulp are used as fuel, livestock feed, and fertilizer. The tree's yellow-brown wood, hard and beautifully grained, is used for furniture.
Olives have been cultivated since ancient times.Long important to Mediterranean peoples, the olive is widely mentioned in classical and Biblical literature. The olive branch has come to symbolize peace and good will.
The Tree
The olive tree reaches a height of 10 to 40 feet (312 m). It is an evergreen that normally lives 300 to 600 years, although some specimens are well over 2,000 years old. The leaves are oblong, smooth-edged, and one to three inches (2.57.5 cm) long. The fragrant flower clusters, called panicles, are made up of many small, white, four-petaled blossoms, similar to lilac blossoms. The trees are pollinated by the wind.
Olive trees are native to the Mediterranean region, where they have been cultivated for about 5,500 years. They are also grown in California (and, to a lesser extent, Arizona), and in Australia, Africa, and Latin America. The trees are raised from cuttings or grafted to seedlings and planted in orchards. They grow well in dry climates in which the soil is well drained but adequately supplied with water. They require much sunlight and are injured by temperatures below 15 F. (-9 C.). Although olive trees thrive in poor soil, the more fertile the soil, the more fruit they produce.
In Europe, the most serious pests attacking olives are the olive moth and olive fly. In California, black scale, parlatoria scale, and the olive knot are destructive.
The Fruit
The olive fruit is, at the most, 1 1/2 inches (4 cm) long and 1 1/8 inches (3 cm) in diameter. It varies from roughly apple-shaped to egg-shaped. When mature, but unripe, the olive is green in color; when ripe, it ranges from yellow through red to purplish black. The fruit is of the type botanists call a drupe; it has a hard pit surrounded by flesh. The mature, ripe flesh is 15 to 30 per cent oil by weight.
Since the fruit is easily bruised, it is picked and handled carefully. Food olives are picked by hand, oil olives with mechanical harvesters. Food olives are picked as they begin to ripen and oil olives are picked after they have ripened.
Olive OilAlthough most of the United States olive crop is used for food, most of the world's crop is used for olive oil. In the United States, undersized olives and those not suitable for use as food are made into oil.
The oil is obtained by crushing the fruit in hand- or machine-operated presses. It is separated from the watery parts of the juice by skimming or by centrifugation Then it is clarified by washing and settling or by filtration.
The first pressing produces virgin oil, a superior grade that is used for salads, cooking, and medicines, and in canning sardines. It is pale yellow in color, odorless, and easily digested, and it keeps well. Edible oil of inferior quality and slightly greener color comes from a second pressing. Further pressings and, finally, chemical extractions remove most of the remaining oil. Oils from these later extractions are used in lubricants, soaps, and ointments.
Olive oil is from 75 to 80 per cent oleic acid and from 8 to 9 per cent linoleic acid, both unsaturated fatty acids. Spain, Italy, Greece, Turkey, and Tunisia are the major producers of olive oil.
Food OlivesFresh olives have an unpleasantly bitter flavor. Olives that are to be eaten are pickled (soaked in brine and lye) to rid them of the bitter flavor. (Green olives are not soaked in lye as long as ripe olives and hence are more bitter tasting.) Ripe olives are made uniformly dark by being exposed to air during the pickling process. The entire process can take several months.
The seeds of pickled olives may be removed by hand or machine to make pitted olives. Pitted olives that are hand stuffed with small pieces of pimiento, onion, melon, almond meat, or anchovy are called stuffed olives. All olives are preserved by being heated at a temperature of 240 F. (116 C.) after they are put into cans or bottles.
Fragments and undersized pickled olives are used in relishes, luncheon meats, and salad dressings, and as seasonings.
In the United States most of the olives produced are ripe olives. Most of the green olives eaten in the United States are imported from the Mediterranean countries.
In California the most important varieties of olive are: the Mission olive, widely raised for both food and oil; the Manzanillo, an early ripening variety; the Sevillano, or Queen, largest Spanish olive; and the Ascolano, a large Italian olive.
The common olive is Olea europaea of the olive family, Oleaceae.