UC Davis Report: 69% of Imported Extra Virgin Samples Fail

A report from the UC Davis Olive Center, released on July 14, found that 69 percent of the imported olive oil samples labeled extra virgin that it bought in California failed the international and USDA sensory standard for extra virgin, against 10 percent of the California samples. The importers’ association has already pushed back. This note covers what was tested, what the objections are, and what it means at the supermarket.

What happened

The study was run by the UC Davis Olive Oil Chemistry Laboratory with the Australian Oils Research Laboratory in Wagga Wagga, New South Wales. Researchers bought 14 imported brands and 5 California brands in one week in March, in three areas: Sacramento, the San Francisco Bay Area and Los Angeles County. Three bottles of each imported brand and two of each California brand were tested.

The Australian sensory panel classed the failing samples as “virgin”, the grade below extra virgin, with defects such as rancid, fusty and musty. The authors, who include the oxidation chemist Edwin Frankel and the Australian lab’s Rod Mailer, give three likely causes: oxidation from heat, light or age; adulteration with cheaper refined olive oil; and poor oil made from damaged or overripe fruit or badly stored. Among the imports, only Kirkland Organic passed the sensory test in all three regions. Among the California oils, one sample of Bariani failed.

The report’s sharpest point is about the tests themselves. The standard IOC and USDA chemistry backed up the tasters’ verdict in only 31 percent of cases. Two newer tests used in Germany and Australia, for diacylglycerols (DAGs) and pyropheophytins (PPP), backed it up in 86 percent. The authors argue those tests should be added to the official standards.

How the trade reacted

The objections came within two days. The day after the release, the Bariani result was questioned because the report’s appendix appeared to show the bottle was past its best-before date; Dan Flynn, the Olive Center’s director, replied that the Australian lab had made a typing error and that the January 2010 date was the bottling date. On July 16 the North American Olive Oil Association, which represents importers, said in a press release that the study used a small sample of 19 oils and some methods the IOC does not recognize. Its president, Bob Bauer, said the association tests more than 200 oils a year, finds problems in fewer than 10 percent, and that its members’ oils are labeled correctly.

Two other facts belong in any fair reading. The research was funded by Corto Olive, California Olive Ranch and the California Olive Oil Council, all with an interest in the result. And the report itself carries a note saying its results should not be used to characterize the quality of olive oil generally.

What it means for buyers

Strip away the argument and the core finding is one the trade has known for years: a lot of oil sold as extra virgin has gone stale or was never very good, and the chemistry in the rulebook is not always sharp enough to prove it. A trained palate catches what the lab misses. Our guide to tasting olive oil blind at home shows how to check a bottle yourself, and our explainer on how olive oil adulteration really works covers the refined-oil blending the new tests are designed to catch.

• Most failures were about age and quality, not seed oil.
• A harvest or bottling date tells you more than the words “extra virgin”.
• Store oil away from heat and light once you open it.

Sources

• UC Davis Olive Center, Tests indicate that imported “extra virgin” olive oil often fails international and USDA standards (July 2010)
• UC Davis News, Most imported olive oils don’t match “extra virgin” claims, study finds (July 14, 2010)
• Olive Oil Times, UC Davis study questioned (July 15, 2010) copy
• Olive Oil Times, Industry group responds to UC Davis olive oil report (July 16, 2010) copy