Extra Virgin Olive Oil
Extra virgin olive oil is made from olives which are cold-pressed from tree-ripened olives. It is produced in many countries and regions including the Mediterranean, the Middle East, Australia, New Zealand, Chile and the United States. Extra Virgin Olive Oil has a relatively low smoke point, so it is used more in salads and as a finishing oil than for frying. The color ranges from bright green to a golden yellow, sometimes with visible solids and crystals. Extra Virgin is high in monosaturated fats, making it a healthier alternative to saturated fat.
Olive oil is made from the crushing and then subsequent pressing of olives. The fact that olives are rich in oil is reflected in the botanical name of the olive tree-Olea europaea-as oleas means oil in Latin.
Olive oil is available in a variety of grades, which reflect the degree to which it has been processed or chemical and sensory defects which may disqualify it from being categorized as extra virgin olive oil. However, there is a broad spectrum of quality represented within the category of extra virgin olive oil as well.
The primary ingredient of olive oil is the oil that is expressed from ripe olives. In the late spring, small flowers appear on the olive trees. Wind pollination results in the blossoming of the olives, which reach their peak oil content approximately six months later. When olives are picked to produce extra virgin olive oil, they can be harvested as early as October in the Northern Hemisphere (Europe, the Middle East, California) and as early as April to as late as July in the Southern Hemisphere (Australia, Chile, Argentina). After they have progressed in color from green to reddish violet to black. It is often necessary to harvest olives from the same trees several times in order to gather olives at the same stage of maturation.
In ancient times, workers knocked the fruit from the trees with long-handled poles. The process has changed significantly over the centuries. Originally, nets were spread under the tree to catch the falling olives. Some producers still shake the tree while others use mechanical harvesting methods such as the colossus olive harvester. Pivotal in producing premium quality extra virgin olive oil is the use of sound fruit which is crushed as quickly as possible, within just a few hours after picking.
One quart (0.95 L) of extra virgin olive oil, the highest level of quality, requires 2,000 olives. The only added ingredient in extra virgin olive oil is the warm water used to flush away the bittemess of the olives, caused by the presence of oleuropein. Extra virgin olive oil contains not more than 1% oleic acid. Pure olive oil, that which results from the second pressing, is often mixed with extra virgin olive oil. The commercial, or non-edible, grades are put through a refining process that may leave traces of soda solutions and bleaching carbons.
Selecting and Buying
* Extra-virgin is the unrefined oil derived from mechanical extraction only, without the use of chemical solvents, and has a free fatty acid value <0.8 and other chemical signs of quality. It is also tested to be free of flavor defects and to have some positive fruity flavor.
* Virgin is also derived by mechanical means but has a higher acidity level than extra virgin olive oil (<2.0) and other chemical quality indicators.
Chemically, the difference between extra virgin olive oil and virgin olive oil involves the amount of free oleic acid, which is a marker for overall acidity. According to the standards adopted by the International Olive Oil Council, "virgin" can contain up to 2% free oleic acid, while "extra virgin" can contain up to 0.8% of free oleic acid.
* "Pure" olive oil is a bit of a misnomer. Don't be fooled if you see the term "pure" on the label; it means the oil is a blend of refined and virgin olive oils.
Another term that you may see on a bottle of olive oil is "cold pressed." This term means that minimal heating was used when mechanically processing the olives to make oil.
Look for premium quality extra virgin olive oil which has been properly stored and then packed fresh upon demand from bulk. Fresh extra virgin olive oil is like fresh squeezed fruit juice: it does not get better with age. Olives are harvested and pressed once a year: in the Northern hemisphere (Europe, the Mediterranean, California) in November or December, and in the Southern hemisphere (Australia, Chile, Argentina) in May, June, or July. Olive oil is at its best within six months of crushing, and should certainly be consumed withing one year. Look for olive oil whose crushing date is clearly indicated on the label, not just a bottling date (which could be long after the olives were crushed, giving the oil time to degrade) or an expiry date (which is often arbitrary, and rarely placed less than 2 years from crushing date).
If fresh, bulk-stored extra virgin olive oil is not available, then look for olive oil packaged in dark tinted bottles with the crush date listed on the bottle. This form of packaging helps protect the oil from oxidation caused by exposure to light. In addition, make sure the oil is displayed in a cool area, away from any direct or indirect contact with heat.
Preparation and Use
Different manufacturers list different smoke points for their olive oils, and some manufacturers list a temperature very close to smoke point as their maximum limit for safe heating of the oil. When these temperatures might be correct for avoiding large amounts of some harmful substances that can be created through heating of the oil, they are not correct limits for preserving the unique nutrients (especially polyphenols) found in high-quality, extra virgin olive oil. Oxidation of nourishing substances found in extra virgin olive oil, as well as acrylamide formation, can occur at cooking temperatures very closer to the 300F range. For these reasons, we recommend a much stricter heating standard involving very little or no heating when enjoying this delightful oil. Studies by the U.S. Food and Drug Administration have found no detectable amounts of acrylamide in olive oil when it is purchased in bottled form and not subsequently used for the frying or baking of foods.
Conserving and Storing
Even though olive oil's monounsaturated fats are more stable and heat-resistant than the polyunsaturated fats that predominate in other oils (especially the easily damaged omega-3 fatty acids found in flax seed oil, which should always be refrigerated and never heated), olive oil should be stored properly and used within a few months to ensure its healthy phytonutrients remain intact and available. Also, be sure to know the date that the extra virgin olive oil was pressed. Olive oil is perishable. Its flavor and phenols are most intact when it is fresh. Consuming extra virgin olive oil that is old reduces the health benefits and can introduce free-radicals if consumed after it has become rancid.
Tinted glass containers screen out some light, but non-reactive dark plastic or metal containers are the best choice for preserving olive oil's beneficial compounds.