Olive oil has long been considered the preferred cooking oil for knowledgeable chefs and food connoisseurs due to its excellent flavor and perceived health benefits. Historically, olive oil has been in use in the Mediterranean for thousands of years, and is a staple of the diet in many countries in that region. In fact, archaeological evidence has shown that olives were turned into oil as early as 4500 B.C.E. by Canaanites in modern-day Israel. Today Spain and Italy are the world’s largest producers of olive oil and are among the countries with the highest consumption rates, along with Portugal and Greece.
Olive oil is composed of a combination of triglyceride esters of oleic, palmitic, and other fatty acids, as well as sterols and other trace elements. Olive oil is produced by pressing whole olives from trees in the Mediterranean Basin. Production begins by crushing or pressing olives to transform them into a paste. The paste is then slowly churned to allow the microscopic droplets of oil to collect. Once the paste has been sufficiently mixed, the oil is separated from the fruit pulp and other liquids using a traditional press or centrifugation, a more modern method. Olive oils are best known for their culinary applications, but they are also used in cosmetics, pharmaceuticals, soaps, fuel, and lubricants.
Not All Olive Oils Are Created Equal
Olive oils are typically classified according to a variety of characteristics including method of pressing, acidity, temperature at which pressing occurs, and the intended use for the oil.
Extra virgin olive oil is considered the highest quality virgin olive oil with superior taste and odor. It is made using virgin, or mechanical, means only and has a free acidity level of 0.8%. Extra virgin olive oil tends to have subtle fruity flavor and is scrutinized according to strict guidelines. In order to be considered extra virgin, an olive oil must not have any defined sensory defects such as rancid, fusty, musty, winey (vinegary) and muddy sediment. These defects are typically due to infected or battered olives, or an inadequate harvest with adverse contact between the olives and the soil. Due to these high standards, extra virgin olive oil accounts for less than 10% of all olive oil in most olive oil-producing countries. Extra virgin olive oil is primarily used for bread, salad dressings, and foods that are eaten cold. It also can be used for sautéing.
Virgin olive oil is created without the use of any chemical treatments to alter the composition, consistency, or flavor of the olive oil. It is of slightly lower quality and taste than extra virgin olive oil. Virgin olive oil typically has a maximum acidity level of approximately 1.5-2% with a still favorable taste.
Refined olive oil is created by applying chemical treatments to virgin olive oil with high acidity levels or other defects. By applying charcoal, physical, and other chemical filters, undesirable strong tastes are eliminated and acid content is neutralized. After the filters are applied, the olive oil has a free acidity of 0.3% or lower. With their lesser quality taste, refined oils are more suitable for deep frying.
Non-virgin olive oil is typically a combination of virgin and refined oil. Lampante oil is olive oil that is extracted by mechanical methods, but is not suitable for human consumption. This is often used for machine lubricants, cosmetics, oil lamps, and soaps.
In addition to being categorized as virgin or extra virgin, many upscale olive oils contain additional refinements to distinguish them from lesser quality oils. Cold or cold extraction means that the olives were not heated over a certain temperature as they were pressed. Temperature is a significant determinant of quality, particularly for extra virgin olive oil. When exposed to heat, unrefined particles in extra virgin olive oil are burned, causing deterioration of the taste. As the temperature to which the olives are exposed under pressure increases, the risk of compromised taste increases as well. Although there is no official consensus, 80°F is generally considered the limit below which the olives must remain during processing in order to be considered cold pressed. In addition to better taste, cold pressed olive oil also retains more nutrients and undergoes less degradation.
First press or first cold pressed are additional quality distinctions for virgin and extra virgin olive oils. First pressed simply means that the olive was pressed mechanically exactly one time. The assumption is that by being pressed only once, the oils released retain a higher level of purity and more flavor than oils produced from olives pressed repeatedly.
The flavor of cold-pressed olive oil can vary considerably due to a variety of factors including the type of olive used in production, the time when the olives are harvested, the temperature at harvest and press, and when they are ground or pressed. Less ripe olives yield more bitter and spicy flavors while riper olives are sweeter in taste. For some connoisseurs, selecting the proper olive oil to complement a particular dish can be as complex as choosing a fine wine pairing since different varieties of olives can have distinctive flavors and shelf-lives that determine their ideal application.
A Healthy Alternative
Studies have shown that those who follow the Mediterranean diet on a long-term basis have a lower risk of heart disease. Many believe this reduced risk is due to the abundant use of virgin and extra virgin olive oil. In fact, the United States Food and Drug Administration allows olive oil manufacturers to indicate that limited scientific evidence has suggested that consumption of two tablespoons of virgin or extra virgin olive oil per day can reduce the risk of coronary heart disease due to the monounsaturated fat in the oil. This assertion is made based on the assumption that the olive oil is used as an alternative to butter, cream, and other substances high in saturated fat. Virgin and extra virgin olive oil are the least processed kinds of olive oil and therefore have more monounsaturated fats and polyphenols than other types of olive oil. Both monounsaturated fat and polyphenols are considered beneficial for heart health. There is further evidence that consumption of olive oil may lower other risk factors for heart disease including cholesterol levels and cholesterol oxidation. It has also been suggested that incorporating virgin and extra virgin olive oil into a diet in place of saturated fats may also affect inflammatory, thrombotic, hypertensive, and vasodilator mechanisms, though scientific evidence has not conclusively confirmed these potential benefits.
Fresh is Always Better
In countries that do not produce olive oil, many people are unaware of the significant difference the freshness of olive oil has on the flavor and overall quality. Like most fresh foods, over time olive oils deteriorate in quality and become stale. Unfortunately, in the United States olive oil is frequently sold in very large containers. Although these may seem like a good value, the large bottles typically require more than a year for the average person to use, meaning the quality significantly degrades before the oil is consumed. Olive oil that is a year or older may still be somewhat pleasant to taste but it is much less aromatic than freshly pressed oil readily available in countries like Spain and Italy. After one year, olive oil should really only be used for cooking. It is no longer suitable for direct consumption with cold foods and salads.