olive oil
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olive oil, oil extracted from the fleshy part of the ripened fruit of the olive tree, Olea europaea. Olive oil varies in color from clear yellow to golden; some varieties obtained from unripe fruit have a greenish tinge. Oils of varying characteristics and qualities are produced by almost every country that grows olives, the variations depending on the district and the ripeness of the fruit.
Uses
Pure olive oil is used largely for culinary purposes and in the preservation of foods, particularly canned fish. It is also used in the textile industry for wool combing, in the manufacture of toilet preparations and cosmetics, in the pharmaceutical industry for medicinal purposes, in the manufacture of high-quality castile soap, and as a lubricant.
Major areas of production
Most of the world supply of olive oil is produced in the countries of the Mediterranean basin, but some is produced in California, South America, New Zealand, and Australia. Leading producers include Spain, Italy, Greece, and Tunisia. While some of the oil produced in the Mediterranean basin is consumed there, a significant portion of it is exported.
Harvest and processing
The timing of fruit harvesting varies depending on geographic location; in general, harvest occurs between September and February in the Northern Hemisphere and between March and September in the Southern Hemisphere. Olives are ready for harvest once they reach maturity. The timing of maturity is influenced by factors such as temperature, sunlight exposure, and soil moisture. Weather that is cool and damp, for example, can delay maturity and sometimes result in fruit being harvested before it has fully ripened in order to avoid risk of frost damage. By contrast, weather that is hot and dry can speed ripening, leading to a relatively brief harvest period. Fruit may be picked by hand or by mechanical harvesting. Once harvested, the fruit is washed clean with water.
To produce high-quality oil, olives must be ground the same day that they are harvested; in this way, the fruit is prevented from deteriorating prior to processing. Oil is obtained from freshly harvested olives by crushing them with a hammer mill, followed by grinding them to produce a paste. The paste is then stirred and softened through a process known as paste beating, or malaxation. Next, solids are separated from liquids via centrifugation, with the liquid portion subsequently subjected to vertical centrifugation to further separate water and fine particulate matter from the oil. After a rest period of 24 to 48 hours, the oil is filtered to remove any remaining particulate matter and is then placed in storage containers.
Grades
Olive oil is broadly classified into several different grades, the most widely known of which are extra-virgin and virgin. Grading is based on standards set forth by the International Olive Council and provides insight into the quality, production method, and best uses of a given olive oil product. Extra-virgin and virgin olive oils are defined by extraction only via mechanical methods; in other words, extraction without the use of heat or solvents. Extra-virgin oil is further distinguished by being free of defects (e.g., no particulate matter), by being fruity, and by having a free fatty acid content (expressed as oleic acid content) that is less than or equal to 0.8 gram per 100 grams. Virgin olive oil, by comparison, has a free fatty acid content between 0.8 and 2. Examples of other grades of olive oil include refined olive oil, which has a free fatty acid content of 0.3 or less and is flavorless and odorless, and Lampante virgin olive oil, which is virgin olive oil determined to have poor flavor and odor and be generally unfit for human consumption without additional processing.
Health benefits
Olive oil is a central component of the so-called Mediterranean diet, which is considered to be especially beneficial for cardiovascular health. Olive oil is rich in antioxidants, including polyphenols, and in healthy monounsaturated fatty acids. Studies of olive oil have shown that its consumption, particularly in the form of extra-virgin olive oil, is associated with lowered risk of cardiovascular disease and type 2 diabetes mellitus and with reductions in brain inflammation and amyloid-beta plaque formation, which are characteristic of Alzheimer disease. Studies in animals have shown that a diet rich in olive oil can in fact help protect against memory loss and learning impairment associated with dementia.
