A dark-tinted glass bottle or a tin.
Exposure to light and heat will destroy an oil’s flavor, which is why you should avoid anything sold in a clear container, especially a plastic one. At home, stow your oil in a cabinet away from the stove.
“Extra virgin” on the label.
Purified and refined oils, labeled simply “olive oil” or “pure olive oil,” are often made with lower-quality, processed oils that have little taste. Extra-virgin oils undergo minimal processing, so their flavor and aroma molecules remain intact.
A harvest or best-by date on the label.
Oil does not improve with age. Look for a date stamp to make sure you are not buying anything more than two years old.
An estate name on the label.
Small producers who grow and press their own olives often include the name of their estate on the bottle. Chances are, you won’t recognize the name, but that doesn’t matter. Having any name on the label is a sign of quality, says Coleman. Almost as good: an official mark or seal showing that the oil comes from a designated region that specializes in producing oils, such as PDO (the European Union’s official Protected Designation of Origin seal) or DOP (a similar seal from Italy).
USDA organic seal.
This certification from the U.S. Department of Agriculture means that at least 95 percent of the oil—either imported or domestic—is made from olives grown without the use of pesticides or synthetic fertilizers. The seal is typically an indicator of a good product, but don’t be alarmed if it’s missing. Many of the finest small olive-oil producers cannot afford to pay for USDA certification.
Forget the old saw that the greener the oil, the better the quality, says Coleman. Color can vary widely, depending on, among other things, the type of olives used and at what point they were pressed.
“First cold pressed” on the label.
This term relates to old-fashioned and rarely used methods of oil production. What’s more, the phrase is not regulated by the USDA or the Food and Drug Administration.
“Product of” on the label.
If an oil is labeled “product of Italy,” that signifies only that the oil was packed and shipped in Italy. The olives could have been grown, harvested, and pressed in, say, Tunisia, Greece, or Spain. To find out where an oil really comes from, look at the estate name.