Olive Oils

Olive oil is the fat extracted from olives, and the grade on the label, from extra virgin down to pomace oil, tells you how the oil was extracted and how clean it tastes.

How to choose Olive Oils

  • Extra virgin or virgin. Both come from olives by mechanical means alone, with no solvents. Extra virgin must taste free of defects and hold no more than 0.8 grams of free acidity per 100 grams. Free acidity is a lab measure of how far the fat has broken down. Virgin oil may show slight defects and reach 2.0 grams.
  • Blend or light. A bottle labeled only as olive oil mixes refined oil with some virgin oil. Extra light on a US label signals mostly refined oil.
  • Harvest date. Pick a bottle that shows one. Extension advice is to use virgin oils within about 18 months of harvest, and a best-by date alone can sit two or three years out.
  • Dark glass or tin. Light sharply shortens the shelf life of oil, and bottles on a top shelf get the most of it.

About Olive Oils

Olive oils are pressed from the fruit of the olive tree and graded by how they were made and how they taste. At the mill, olives are crushed to a fine paste, stirred slowly for 45 minutes or more, and spun in a decanter that separates the oil from water and solids.

Virgin oils go from there to settling tanks and the bottle. Oil with taste defects is refined, which strips its color and flavor, and pomace oil is pulled from the leftover paste with solvents. The US grade standard says pomace oil may not be labeled olive oil.

Keep a bottle sealed, dark and away from the stove or a sunny window, since oil left in light or near heat loses freshness faster. Buy a size you can finish within a couple of months of opening.

At a glance

Made from
Crushed olives; virgin oils mechanically extracted, pomace oil solvent-extracted
Main types
Extra virgin, virgin, refined blend, pomace oil
Unopened
Virgin oils within about 18 months of harvest
Once opened
Use within a couple of months

Olive Oils questions

What does cold extraction mean on an olive oil label?

Under European Union labeling rules, cold extraction may appear only on extra virgin or virgin oil separated from the paste below 27°C, about 81°F. The oil must come out by a centrifuge, which spins it free, or by percolation, which lets it drip out. First cold pressing has the same temperature limit and also requires an old-style hydraulic press. Most mills now use centrifuges, so cold extraction is the phrase you will see more often.

Should olive oil be kept in the refrigerator?

It is not needed. The International Olive Council recommends 55 to 77°F and notes that cold slows oxidation but can turn the oil cloudy and solid, a change that reverses as it warms. Oklahoma State extension warns that condensation from chilling can cause off flavors. A cool, dark cupboard suits a bottle you will finish within a few months, and the IOC names light as the main threat to quality.

What do fruity, bitter and pungent mean in olive oil?

They are the three positive qualities tasters look for in extra virgin oil. Fruity is the fresh aroma of sound olives, green or ripe. Bitter is a taste on the tongue, and pungent is the peppery catch at the back of the throat. Neither counts as a defect, and like the rest of an oil's flavor they fade with time, so a recent harvest shows them most clearly.

Sources: USDA Agricultural Marketing Service; International Olive Council; Oklahoma State University Extension.

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