The US recognizes two types of olive oil: ``virgin'' olive oil and ``pure'' olive oil. Grading olive oil is a tricky business. There are legal definitions, based on acidity, and also casual definitions, says food writer Michele Anna Jordan. Even within designated categories, quality can vary. The best way to test olive oil is by taste. A few helpful definitions:
* VIRGIN OLIVE OIL is oil obtained solely by physical or mechanical methods (as opposed to chemical) and can have an oleic-acid level of no more than 3 percent. Oleic acid is one of the mono-unsaturated fatty acids in olive oil. Virgin olive oil is further classified by percentage of acid:
Extra-virgin olive oil is considered top-of-the-line, offering the widest range of flavor and aroma. It contains no more than 1 percent oleic acid. First pressing and cold pressing (usually with granite stones) of hand-picked olives yield the most superior oil.
Super-fine, fine, and semi-fine virgin olive oils are not commonly found in the US. They contain more oleic acid than extra-virgin olive oil, respectively, but no more than 3 percent.
* `PURE' OLIVE OIL, is still 100 percent olive oil, but it is a blend of refined olive oil and virgin olive oil - to add back some flavor and color that the refining process removed.