So as to be classified as extra virgin, the oil itself has to come from the first press of the freshly harvested and undamaged olive fruit. During this process there can be absolutely no use of chemicals or excessive heat to be able to preserve the integrity of the oil. Once the oil has been extracted, it is subject to rigorous tests to ensure it is up to the standards that are required to label an olive oil"extra virgin."
Olive oils expecting to be labeled"extra virgin" have to pass a variety of chemical and tasting tests prior to going on the shelf for customers to purchase. A taste test is performed by a trained tasting panel (like California's own California Olive Oil Council, or COOC, tasting panel) to ensure the oil is defect-free and retains desirable attributes such as olive fruitiness. Chemical tests are performed in order to measure the oil's attributes, such as quality of fruit, milling, freshness, and overall handling.
Unlike wine, olive oil does not get better with age -- it is best when fresh. If you want the freshest olive oil, purchasing California-produced extra virgin olive oil is a necessity!