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Q&A: Olive oil

By GUI ALINAT
Published February 23, 2005

	Essential oils The rise of California's estate olive oils has cooks learning what the world has long known: the oil can be as varied and sophisticated as wine. A taste of the sublime and the olive drab If you think all olive oil is created equal, a tasting party will change your mind. Q & A: Olive oil

How is olive oil made?

Harvests generally come between early November and late December, when olives have started to ripen, and begins when the olives on a tree are about 60 percent black (ripe) and 40 percent green (not ripe). Harvesters place nets on the ground and beat the trees with long sticks, causing the olives to fall. More careful harvesters use large combs so as not to bruise the delicate olives. Olives are then crushed whole, in granite millstones, within the first 24 hours of picking to preserve their naturally low acidity. The pulp is pressed and the liquid (water and oil) is collected for the final separation in a centrifugal separator.

"Cold-pressed" olives have been pressed without using heat. Heat increases yields but deteriorates the quality of the oil. Virtually all extra-virgin olive oil is cold-pressed.

Labels such as extra-virgin, virgin and pure categorize olive oils according to their acidity. Extra-virgin olive oil is the first, cold-pressing of the olives with an acidity level no higher than 1 percent. It is the oil of the highest quality, and boasts a perfect, fruity taste and color. Virgin olive oil is also cold-pressed, but has a level of acidity between 1 percent and 3 percent, making it slightly less appealing than extra-virgin.

Pure olive oil has been refined with the use of charcoal and other chemical and physical filters to decrease acidity. A label with the mention "olive oil" (as opposed to extra virgin/virgin olive oil) is an oil consisting of a blend of pure olive oil and virgin olive oils fit for consumption. It has an acidity level of less than 1 percent but that has been obtained by mixing pure oil with a flavorful virgin oil. The "light" designation refers to flavor, not caloric content, as all olive oil has the same amount of calories, about 120 per tablespoon and 14 grams of fat. In the United States, flavorless and often low-quality pure oil is sold as "light" or "lite" oil for a premium price. There is no official definition of lite olive oil.

The color of the oil will not reliably predict the taste of the oil. Greener oils are usually pressed from early-season olives. Some varieties have a greener or more golden oil than others, but oils are often blended from several varieties.

Although olive oil may be good for a year, it is best to buy no more than you can use in 60 to 90 days. Once opened, it can become rancid. Store oil in a cool, dark place. Ceramic containers or tins are fine.

[Last modified February 22, 2005, 09:56:04]