Extra-virgin olive oil is the cream of the olive oil crop. It is extracted from the olives with the first pressing with no chemicals additives to help the process, as with other types. This quality, clear oil has low acid levels and a fruity taste reminiscent of the pressed olives. Not all oils from the first pressing qualify as extra-virgin. The International Olive Council must approve all olive oils that carry the extra-virgin label.
Virgin olive oil is a common component in most recipes. Like extra virgin, it comes from the first cold pressing of the olives. It has a stronger flavor and usually is more acidic, which is why it is not extra-virgin. Virgin oil is much less expensive than extra-virgin varieties and is also more readily available. It comes in several grades, from fine to semifine. The finer the grade, the more suitable the oil for use as a flavoring agent.
Refined and Pure Oils
Refined oils are from the olives using chemical practices. The extraction method removes much of the flavor and color from the oil, but it does produce a shelf-stable product that doesn't spoil or go rancid easily. Refined oils are suitable only for cooking because of their lack of flavor. Virgin oil is sometimes combined with refined oil to produce pure olive oil, which has the distinct olive oil flavor but the longer shelf life of a refined oil. Pure oils do not have the quality of true virgin oils.
Pomace oils do not have the nutritional benefits of other olive oils because of solvents used to extract the oil. The pomace is the part of the olive that remains after extraction of higher quality oils. It has no flavor, odor or color, and is only suitable for cooking when an olive oil flavor is undesirable in the finished dish. Pomace oil is the lowest quality of olive oil and also the least expensive.
Light or Mild Oils
Light or mild oils, similar to pure, combine virgin oil with a lesser quality oil. They have no color or flavor, making them suitable only in cooked dishes. Light oils are used primarily to replace other oils and fats in baked goods and recipes when the flavor of true olive oil isn't desired.