Olive oil is a vegetable oil obtained from the fruit of the Olive tree (Olea europaea L.), a traditional tree crop of the Mediterranean Basin. It is used in cooking, cosmetics, soaps and as a fuel for traditional oil lamps. Olive oil is regarded as a healthful dietary oil because of its high content of monounsaturated fat (mainly Oleic acid) and polyphenols.

Grades and classification

The International Olive Oil Council (IOOC) sets standards of quality used by the major olive oil producing countries. It officially governs 95 percent of global production, and holds great influence over the rest. IOOC terminology is precise, but it can lead to confusion between the words that describe production and the words used on retail labels. Olive oil is classified by how it was produced, by its chemistry, and by its flavor. All production begins by transforming the olive fruit into olive paste. This paste is then malaxed to allow the microscopic olive droplets to concentrate. The oil is extracted by means of pressure (traditional method) or centrifugation (modern method). After extraction the remnant solid substance, called pomace, still contains a small quantity of oil.

Industrial grades

The several oils extracted from the olive fruit can be classified as:

• Virgin means the oil was produced by the use of physical means and no chemical treatment. The term virgin oil referring to production is different from Virgin Oil on a retail label.

• Refined means that the oil has been chemically treated to neutralize strong tastes (characterized as defects) and neutralize the acid content (free fatty acids). Refined oil is commonly regarded as lower quality than virgin oil; the retail labels extra-virgin olive oil and virgin olive oil cannot contain any refined oil.
• Olive-pomace oil means oil extracted from the pomace using chemical solvents — mostly hexane — and by heat.

Quantitative analytical methods determine the oil's acidity, defined as the percent, measured by weight, of free oleic acid in it. This is a measure of the oil's chemical degradation — as the oil degrades, more fatty acids get free from the glycerides, increasing the level of free acidity. Another measure of the oil's chemical degradation is the peroxide level, which measures the degree to which the oil is oxidized (rancid).

In order to classify olive oil by taste, it is subjectively judged by a panel of professional tasters in a blind taste test. This is also called its organoleptic quality.

Retail grades

The IOOC standards are complicated. The labels in stores, however, clearly show an oil's grade:

• Extra-virgin olive oil comes from the first pressing of the olives, contains no more than 0.8% acidity, and is judged to have a superior taste. There can be no refined oil in extra-virgin olive oil.

• Virgin olive oil with an acidity less than 2%, and judged to have a good taste. There can be no refined oil in virgin olive oil.

• Olive oil is a blend of virgin oil and refined virgin oil, containing at most 1% acidity. It commonly lacks a strong flavor.

• Olive-pomace oil is a blend of refined olive-pomace oil and possibly some virgin oil. It is fit for consumption, but it may not be called olive oil. Olive-pomace oil is rarely found in a grocery store; it is often used for certain kinds of cooking in restaurants.

• Lampante oil is olive oil not used for consumption; lampante comes from olive oil's ancient use as fuel in oil-burning lamps. Lampante oil is mostly used in the industrial market.

Label wording

Olive oil vendors choose the wording on their labels very carefully.

• "Imported from Italy" produces an impression that the olives were grown in Italy, although in fact it only means that the oil was bottled there. A corner of the same label may note that the oil was packed in Italy with olives grown in Spain, Italy, Greece, and Tunisia. Since Spain produces nearly half of the world's olive harvest, it is likely the oil "imported from Italy" comes from olives grown in Spain.

• "100% Pure Olive Oil" sounds like a high-end product, but in fact is often the lowest quality available in a retail store: better grades would have "virgin" on the label. Having said that, 100% pure olive oil might be perfect for baking and frying, since high heat can destroy the rich flavor of extra-virgin oil.

• "Made from refined olive oils" suggests that the essence was captured, but in fact means that the taste and acidity were chemically produced.

• "Lite olive oil" suggests a low fat content, whereas in fact it refers to a lighter color. All olive oil—which is, after all, fat—has 120 calories per tablespoon (33 kJ/ml).

• "From hand-picked olives" gives the impression that extraordinary care went into the oil's production, whereas it is not clear that a manual harvest produces better oil than the common tree-shaking method.

The market

The International Olive Oil Council is an inter-governmental organization based in Madrid, Spain that promotes olive oil around the world by tracking production, defining quality standards, and monitoring authenticity. More than 85% of the world's olives grow in the 23 nations that are members of the Council.

The United States is not a member of the IOOC, and the United States Department of Agriculture does not legally recognize its classifications (such as extra-virgin olive oil). The USDA uses a different system, which it defined in 1948 before the IOOC existed. The California Olive Oil Council, a private US trade group, is petitioning the Department to adopt terminology and practices that shadow the IOOC's rules.

Among global producers, Spain leads with more than 40% of world production, followed by Italy and Greece. Much of the Spanish crop is exported to Italy, where it is both consumed and repackaged for sale abroad as Italian olive oil. Although boutique groceries sell high-quality Spanish olive oil at a premium, Italian olive oil has the popular reputation for quality.

Olive oil extraction

Main article Olive oil extraction

Traditionally, olive oil was produced by beating the trees with sticks to knock the olives off and crushing them in stone or wooden mortars or beam presses. Nowadays, olives are ground to tiny bits, obtaining a paste that is mixed with water and processed by a centrifuge, which extracts the oil from the paste, leaving behind pomace.

Health claims

In the United States, producers of olive oil may place the following health claim on product labels:

Limited and not conclusive scientific evidence suggests that eating about two tablespoons (23 grams) of olive oil daily may reduce the risk of coronary heart disease due to the monounsaturated fat in olive oil. To achieve this possible benefit, olive oil is to replace a similar amount of saturated fat and not increase the total number of calories you eat in a day.

This decision was announced November 1, 2004 by the Food and Drug Administration after application was made to the FDA by producers. Similar labels are permitted for walnuts and omega-3 fatty acids which also contain monounsaturated oil[6].

A health study in 2005 compared the effects of different sorts of olive oil on arterial elasticity. Probands were given a serving of 60 grams of white bread and 40 milliliters of olive oil each morning for two consecutive days. The study was conducted in two stages. During the first stage, the probands received polyphenol-rich oil ("extra virgin" oil contains the highest amount of polyphenols), during the second, they received oil with only one fifth the phenolic content. The elasticity of the arterial walls of each proband was measured using a pressure sleeve and a Doppler laser. It was discovered that after the probands had consumed olive oil high in polyphenols, they exhibited increased arterial elasticity, while after the consumption of olive oil containing less polyphenols, they exhibited no significant change in arterial elasticity. It is supposed that, in the long term, increased elasticity of arterial walls reduces vascular stress and consequentially the risk of two common causes of death - heart attacks and stroke. This could, at least in part, explain the lower incidence of both ailments in regions where olive oil and olives are consumed on a daily basis.

In addition to the internal health benefits of olive oil, topical application is quite popular with fans of natural health remedies. Extra Virgin Olive Oil (EVOO) is the preferred grade for moisturizing the skin, especially when used in the Oil Cleansing Method (OCM). OCM is a method of cleansing and moisturizing the face with a mixture of EVOO, castor oil (or another suitable carrier oil) and a select blend of essential oils.

Olive oil in history

One of the earliest documented historical uses of olive oil is in religious ceremonies of the ancient Minoans. Olive oil was a central product of the Minoan civilization, where it is thought to have represented wealth. The Minoans put the pulp into settling tanks and, when the oil had risen to the top, drained the water from the bottom. It was also very common in the cuisine of Ancient Greece and classical Rome. According to legend, the city of Athens obtained its name because Athenians considered olive oil more essential than water, thus preferring the offering of the goddess Athena over the offering of Poseidon.

Olive Oil was also used by the ancient Hebrews. Olive oil of the highest purity was poured daily into the seven cups of the golden candelabrum (called the Menorah) in the Holy Temple in Jerusalem. Olive oil was also used for anointing the kings of Kingdom of Israel.

From this ritual of anointing, the expected savior of the Jews is called the Messiah (מָשִׁיחַ "anointed one" -- mashiach). The word Christ (Greek Χριστός, Khristos, "the anointed one") is a literal translation of "mashiach".

Historically, olive oil has been used for medicines, as a fuel in oil lamps, and to make soap.

The importance and antiquity of olive oil can be seen in the fact that the word "oil" actually derives from the same root as "olive".

Olive oil in contemporary religious use

Used as a medicinal agent in ancient times, and as a cleanser for athletes (athletes in the ancient world were slathered in olive oil, then scraped to remove dirt), it also has religious symbolism related to healing and strength and to "consecration" -- God's setting a person or place apart for special work.

While other fuels are allowed, Jews prefer to use olive oil to fuel the 9-branched candelabrum (called a menorah or a hannukiah) used to celebrate Judaism's holiday of Hanukkah.