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Davis, California

Thursday, June 13, 2024

UC Davis study uncovers olive oil fraud

Many of the of the olive oils sold as top-grade “extra virgin” are not what their labels claim, according to a new study from the UC Davis Olive Center. Authentic extra virgin oil has more complex flavors and is milled without heat or chemical solvents. As the top grade of olive oil, extra virgin also commands the highest price.

The study, which analyzed 19 popular brands labeled as “extra virgin,” found that 69 percent of imported olive oils – but only 10 percent of Californian oils – failed extra-virgin tests.

The study used a variety of chemical tests as well as a sensory panel evaluation to determine whether each sample was up to international quality standards.

Dan Flynn, executive director of the Olive Center, said the samples failed for three reasons: they were rancid from age, adulterated with cheaper refined olive oil, or they were poor-quality oils made from damaged, mishandled or overripe olives. Surprisingly, samples of oil from popular brands Bertolli and Carapelli did not pass the test.

“Our hope is that these findings will lead to improved methods for evaluating extra-virgin olive oil, and increased consumer confidence that ‘extra virgin’ on the label means extra virgin in the bottle,” Flynn said.

Olive oil fraud hurts the consumer as much as the industry, said Mike Madison, a local olive farmer who sells olive oil at the Davis Farmers Market. Adulterated oil is hard to compete with financially, but the prevalence of mislabeled oil may be even more damaging.

“The worst thing is that it gives people the wrong idea about olive oil,” Madison said. “It’s like if you tried a really bad wine the first time and then you thought all wine was awful.”

The North American Olive Oil Association (NAOOA), a trade association representing marketers, packagers and importers of olive oil, expressed the same concern for the industry’s image. Bob Bauer, president of NAOOA questioned the validity of the Olive Center findings.

“The objectivity of the whole study is greatly in question. It was funded by the California olive industry, which has a motive for finding these kinds of results,” said Bauer.

“We’ve had our tests going for approximately 20 years, with 200 samples a year, and we have quite a body of results that don’t say this at all.”

While NAOOA contests the results, there are steps consumers can take to ensure they are buying quality oil.

Nicole Sturzenberger, assistant director of the Olive Center, advises consumers to shop for mid-priced extra virgin oil. Buying authentic extra virgin oil ensures that the oil is pure, fresh and suitable for cooking. More expensive oils tend to have more complex, interesting flavors, but these flavors come from volatile compounds that burn away when the oil is heated over roughly 90 degrees Fahrenheit, which is why these oils are always “cold-pressed.”

“As the oil heats, you release volatile compounds and you lose a lot of flavor and character,” Sturzenberger said.

Mike Madison offered another piece of advice: don’t buy olive oil stored in clear glass.

Oil in clear glass oxidizes and turns rancid like the defective samples in the study, Madison said. Olive oil should be stored at room temperature in dark glass and consumed as soon as possible after the harvest date.

EMILY GOYINS can be reached at science@theaggie.org.


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