Study Confirms: Most Imported Extra-Virgin Olive Oil Sold in California Is the Pits

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A new study has found that 69% of imported "extra-virgin" olive oil sold in California is sub-standard.

Last week's olive oil news has now been confirmed: Most imported olive oils sold in California that claim to be "extra-virgin" are not, according to a just-released study by researchers at UC Davis and the Australian Oils Research Laboratory.

Using chemical and sensory analysis, study participants found that 69% of sampled imported oils failed to meet internationally accepted standards for extra-virgin olive oil. In comparison, only 10% of California-produced oils failed to meet the standards.

In March, the researchers sampled "extra-virgin" olive oils bought in California supermarkets and "big box" stores. (The complete report names the 19 brands tested.)

"The intent of the study was to provide consumers and retailers with an accurate picture of the quality of olive oils now being marketed through grocery stores and other retail outlets in California," said Dan Flynn of UC Davis' Olive Center, which conducted the study along with colleagues in Australia.

To be deemed extra-virgin, the oil must be extracted from olives without heat or solvents, unlike cheaper refined oils. Some of the tested oils had oxidized. Others were found to be adulterated with cheaper olive oil or to have been made from damaged and overripe (read: rotten) olives. Still others were rendered unpalatable through processing flaws or improper storage.

"Before this study, we had anecdotal reports of poor-quality olive oil being sold as extra-virgin," Flynn said. "Now there is empirical proof. The oils that failed in our tests had defects such as rancidity--many of these oils just did not taste good."