By Lori Zanteson
Olive Oil Times Contributor | Reporting from Los Angeles

Last year’s report by the UC Davis Olive Center, “Tests indicate that imported ‘extra virgin’ olive oil often fails international and USDA standards,” caused a stir in the olive oil industry and beyond when popular media trumpeted the results with fantastic headlines like “That Olive Oil Is No Virgin“.  The controversial study by the California university stated that 69 percent of imported olive oil samples labeled “extra virgin olive oil” failed international chemical and sensory standards for extra virgin classification.

davis-olive-center-responds-to-ioc-criticism-of-reportThe Chemistry Expert Group of the International Olive Council (IOC) took exception to the findings andpublished a rebuttal, citing the small sampling size, unknown storage conditions, chemical testing methods, and sensory analyses of the study.

Now the authors of the report have issued their own pointed response to these criticisms, defending each exception brought by the IOC chemists in a statement first published on the website of the American Oil Chemists’ Association.

“In my view,” the study’s lead scientist, Dr. Edwin Frankel, wrote in an email to Olive Oil Times, “the IOC has been very politicized in establishing standard for exported extra virgin olive oils. In California, we hope to be able to develop better standards in support of our locally produced extra virgin olive oils.”

UC Davis Stands Behind the Report
Edwin N. Frankel, Rodney J. Mailer, Selina Wang, Charles F. Shoemaker, and Dan Flynn

The response to the University of California Davis report (“Tests indicate that imported ‘extra virgin’ olive oil often fails international and USDA standards,” UC Davis Olive Center, July 2010) has ranged from knowing nods to sharp criticisms such as those offered by the Chemistry Expert Group of the International Olive Council (IOC; Madrid, Spain). We respect the members of the Expert Group but stand fully behind the report.

To quickly review the source of the controversy, the UC Davis study found that 69% of the imported olive oils that we tested failed the IOC’s official sensory test, with that result confirmed in 31% of the cases by the IOC’s tests for UV absorbance of oxidation products, and in 86% of the cases by German diacylglycerol (DAG) and pyropheophytin (PPP) tests.

The report was completed by the UC Davis Olive Center and the Australian Oils Research Laboratory. The Australian laboratory is recognized by the IOC and the AOCS for proficiency in conducting IOC chemical and sensory tests.

While the Expert Group’s statement does not adequately represent the diversity of opinion among members of the panel, many of whom were not offered an opportunity to review or sign the statement, we will respond to the statement as written.

Statistical significance. The IOC Expert Group asserts that the UC Davis report is “not statistically significant,” but actually UC Davis analyzed samples at four times the rate of the IOC’s own quality control program (on an annualized basis). According to an official IOC report available from the IOC website, the IOC analyzed an average of 116 extra virgin samples per year in 2008 and 2009 collected from the United States and Canada. These countries have a combined population of 340 million, so the IOC analyzed one sample for every 2.93 million people. The UC Davis study is based on 52 samples collected from the state of California, which has a population of 38 million. Thus, the UC Davis study analyzed one sample for every 730,000 people, or at four times the rate of the IOC.

Storage conditions. The Expert Group, while accepting our findings that many oils were noncompliant with IOC standards, contends that “it is impossible to consider the results reliable” without information on shipping or time of testing. Here is the factual information: All oil samples were collected and managed at UC Davis by a single member of the research team. Samples were collected within a seven-day period when daytime temperatures ranged between 52°F and 56°F (11°C and 13°C). The samples were in transit to UC Davis for no more than nine hours. The research team promptly coded, wrapped in foil, packaged for shipment, and shipped the samples to the Australian lab, with the samples arriving in Australia five days after shipment. The Australian Oils Research Laboratory is IOC-certified and follows IOC quality standards relating to time of testing and all other parameters.

Chemical methods. The Expert Group states that the IOC trade standard “contains all the necessary methods to assess the quality and purity of olive oil . . . hence it was not necessary to apply the nonofficial methods cited in the report.” While we appreciate the work that the IOC has performed in developing standards, we expect that few chemists would agree that IOC standards are fully adequate, and we feel strongly in supplementing IOC methods with additional tests (DAG and PPP) adopted in Germany and Australia. In fact, the German/Australian chemical tests confirmed negative sensory results for 86% of the cases, whereas the IOC chemical tests confirmed negative sensory results for just 31% of the cases.

The Expert Group also states that it rejected the DAG and PPP tests because “these compounds change dynamically during the shelf life of the oil.” Using this reasoning, the panel would also need to disavow IOC tests for free fatty acidity, conjugated dienes (K232) and trienes (K270), and peroxide values, which all would change during the shelf life of the oil. The Expert Group also says that the UC Davis study cannot conclude that refined oils were added because the stigmastadienes and sterol profiles were in compliance with IOC standards. Actually, the UC Davis study indicated that the addition of refined oils was a possibility, and our study team concluded “if any of the samples were adulterated, it is most likely that the adulterant was refined olive oil rather than refined nut, seed, or vegetable oils.”

Sensory analysis. The Expert Group, while accepting our finding that many of the oils failed the sensory analysis conducted by an official IOC panel, says that IOC procedures require a second analysis to be performed by another IOC panel, and faults the UC Davis study for not having a second test conducted. Actually, the IOC does not require a sensory panel to get a second opinion when a panel finds that an oil sample has failed an initial test.

Although the UC Davis report was just one study, and should be viewed as such, we should note that serious olive oil quality problems were found by Consumer Reports in September 2004, Der Feinschmecker in May 2005, Australian Oils Research Laboratory over several years, the University of the Republic in Uruguay in October 2010, and the Department of Health in Andulacía, Spain, in November 2010. With the United States now being the third-largest consumer of olive oil in the world, this issue deserves continued research.

We encourage readers to examine our Report and Appendix, and assess the validity of the study for themselves. We reiterate our desire to work collaboratively with the IOC to analyze the quality of olive oil in the United States. Let’s test it and taste it together.

Edwin N. Frankel is an adjunct professor, Selina C. Wang is a research associate, Charles F. Shoemaker is professor and leader of the UC Davis Olive Oil Chemistry Laboratory, and Dan Flynn is the executive director of the UC Davis Olive Center, all at the University of California, Davis. Rodney Mailer is a research fellow at the Australian Oils Research Laboratory in Wagga Wagga, Australia.


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