Point-counterpoint on UC Davis olive oil report

By Edwin N. Frankel, Rodney J. Mailer, Selina Wang, Charles F. Shoemaker, and Dan Flynn

In This Section

January 2011

The International Olive Council (IOC; Madrid, Spain) is a nonprofit, intergovernmental organization formed in 1959 under the auspices of the United Nations. IOC's prime concerns include the prevention of fraud and the protection of consumers. The harmonization and fulfillment of official standards and the application of official methods are of key importance in achieving greater transparency and fair trade. It is important for the authorities of importing countries to harmonize and comply with the official IOC standards, and it is their responsibility to guarantee product quality and protect consumers. IOC standards are developed and revised in light of scientific, technological, and commercial advances.

The Council of Members of the IOC is the forum where members draw up and adopt rules by consensus for the quality improvement and quality control of olive products in order to facilitate a fair international market for olive oils, olive-pomace oils, and table olives and so stimulate consumption of these products. Speaking as the intergovernmental point of reference for olive products standardization, the IOC urges the competent authorities of producing and importing countries to harmonize their rules and regulations and offers its cooperation on any issues that might arise.

The IOC currently has 17 member states. Membership is open only to the governments of states with responsibilities for the negotiation, conclusion, and application of international agreements, especially commodity agreements.

Article 1(2) of the General Objectives of the International Agreement on Olive Oil and Table Olives, 2005 is to develop the definitions and analytical characteristics of all the grades of olive oils and olive-pomace oils included in the trade standards adopted by Members for  compulsory application in international trade.

IOC standards are revised and updated in light of scientific advances that help to make testing methods more accurate, or of technological and commercial developments. Expert chemists and sensory analysts designated by member countries study and develop testing methods to determine the quality and to control the purity of olive oils and olive-pomace oils. Representatives of standards agencies and institutions from nonmember entities such as AOCS, the Codex Alimentarius Commission (CAC), California Olive Oil Council, Canadian Food Inspection Agency, United States Department of Agriculture, Australian Olive Association, North American Olive Oil Association (NAOOA), and the International Organization for Standardization (ISO) are also invited to attend meetings.

Methods are constantly being improved to adapt them to industry needs and technological developments. Before a method of analysis is approved by the IOC, ring tests are conducted at laboratories to validate the method. For a method to be made final, its precision data must be checked and its applicability to olive oil be confirmed. Once adopted, the IOC fixes the permissible limits for each parameter and grade and includes them in its trade standard.

The testing methods recommended by the IOC are included in the current trade standard. Both the standards and the methods, the latter referenced as COI/T.20, are posted on the IOC website (www.internationaloliveoil.org) as they are reviewed and adopted.

Ever since its initial involvement in the standardization of olive products, the IOC has cultivated a solid cooperative relationship with a number of international organizations-including CAC, the World Customs Organization, ISO, and the European Union-to define the minimum compositional, quality, and purity requirements of olive oils and to harmonize the methods of analysis in use. The CAC is responsible for the joint FAO-WHO (UN Food and Agricultural Organization-World Health Organization) program for the development of food standards with an eye to consumer health protection and fair trade. The World Trade Organization (WTO) takes into account the standards and recommendations of the CAC in the application of the WTO Agreements on Sanitary and Phytosanitary Measures (SPS Agreement) and Technical Barriers to Trade (TBT Agreement). The CAC standards for olive oils and table olives are currently being revised to bring them into line with the IOC trade standards.

The IOC runs a quality recognition scheme for physicochemical and sensory testing laboratories (tasting panels) aimed at increasing mutual confidence between testing facilities and heightening the confidence of the olive business sector in laboratories. The IOC annually recognizes laboratories and panels that fulfill its requirements and satisfactorily pass the proficiency check tests it holds every year. 

In 2009/10 a total of 40 tasting panels obtained IOC recognition; 56 panels took part in the two check tests arranged for 2010/11. Forty-eight physicochemical testing laboratories obtained IOC recognition in 2009/10, and 62 are participating in the 2010/11 ring test. The list of recognized laboratories and panels is posted on the IOC website and updated every year.

The test certificates issued by recognized panels can carry legal weight in disputes. Each country is responsible for official product control. The IOC also sponsors a voluntary, self-regulatory scheme currently in place in Australia, Brazil, Canada, and the United States, where exporters, importers, and distributors of olive oil and olive-pomace oil are required to adhere to IOC standards in order to help achieve orderly market development and fair trading. In the case of North America (USA and Canada), this quality control scheme has been operating since 1991 under an agreement signed by the IOC with the NAOOA to undertake product quality control at recognized laboratories using updated methods of analysis and taking into account the designations and quality criteria specified in the IOC standards.

Some 200 samples of imported oils sold in the United States are chemically tested every year by the IOC under the quality control scheme, and the labeling also is checked to ensure that the product contents tally with the labeling declarations. According to IOC findings, anomalies are detected in less than 10% of the imported oils analyzed; NAOOA is notified of the nature of the irregularities with a view toward taking action.

In July 2010, the UC Davis Olive Center released a report on olive oil labeling that caused a ripple in the media. The report applies methods that have not been validated or adopted by the IOC.

In doing so, the Chemistry Expert Group of the IOC feels that an attempt has been made to distort reality by giving data that, taken out of context and without knowledge of the technical background, might mislead consumers and seriously damage the image of olive oil.

In view of all these considerations, the IOC group of experts on olive oil chemistry and standardization officially designated by the IOC member states signed a consensus document (below) in which they express their unanimous technical opinion on the UC Davis study. The statement was signed on October 8, 2010, by 27 experts from laboratories recognized by the IOC and officially designated by 15 countries.

Statement by the Chemistry Expert Group

A report issued by the UC Davis laboratory questioning the trueness-to-grade of extra virgin olive oil imported into the United States has been published recently in various news media. The IOC Chemistry Expert Group have discussed this subject at their latest meeting.

The Group is made up of expert chemists from almost all the IOC member and nonmember countries (Australia, Canada, and the United States) and international organizations (AOCS, Codex Alimentarius Commission, and the ISO). The main aim of the group is to study testing methods and revise them when necessary to determine the quality and control the purity of olive oils and olive-pomace oils. Methods are constantly being improved to adapt them to industry needs and technological developments.

IOC standards are revised in light of scientific advances that help to make testing methods more accurate, or of technological and commercial developments. Their aims are to enhance and control quality, as well as to ensure transparency on the international market for olive oils, olive-pomace oils, and table olives, and to promote their consumption.

Considering the report published by UC Davis, there are several points this Expert Group wishes to clarify.

The results reported are for only 52 samples of 19 brands. This is not statistically significant of the olive oil imported into the United States, because samples traded in three cities of California are not representative of the whole olive oil market in the country; therefore, the claim questioning the trueness-to-grade of imported extra virgin olive oil is not realistic.

There are no details of storage conditions during shipping or time of testing. Without this information, it is impossible to consider the results to be reliable. In addition, the recommendations stated on the product labels indicate that the oils must be kept in a cool, dry place and must not be exposed to direct light in order to comply with their assigned grade classification during their shelf life. We do not know if the noncompliance with the standards was due to the original characteristics of the oils or to storage conditions.

The IOC trade standard is under constant supervision by the IOC Chemistry Expert Group and 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.

Most of the samples were misclassified by the sensory analysis. The official method of the IOC was used, but was not applied according to the standardized procedure described in the method. When the grade assigned by the sensory analysis does not match the grade stated on the label classification, the procedure requires a second analysis to be performed by another IOC-recognized panel. This was not done in the UC Davis study.

The UC Davis study places particular emphasis on the application of nonofficial methods and gives the impression that the IOC methods are not sufficient to assess the quality and purity of olive oil. We would like to stress that some of the methods used in this study are not IOC methods, even though IOC methods are available (polyphenols and triacylglycerol) to assess the same parameters.

It is also important to point out that the IOC does have an official method to detect low-quality oils or the addition of soft refined oils obtained from low-quality oils (alkyl esters of fatty acids). Instead, the study used nonofficial methods that analyze 1,2-diacylglycerol and pyropheophytins content. These methods had already been studied by the IOC Chemistry Expert Group, which concluded that the scope of these methods could not include the assessment of the quality and purity of olive oil because these compounds change dynamically during the shelf life of the oil.

In this context, the UC Davis report claims that cheap refined oil was added to the oils they tested; however, all the parameters (stigmastadienes and sterol composition) that detect the addition of this type of oil were within the limits. Consequently, they cannot conclude that refined oils were added.

As the IOC Chemistry Expert Group, we are very concerned about the final recommendations of the study advocating the implementation of methods that have not been proven to have any relationship with the quality or purity of olive oils.

The Group wishes to end by saying it is ready and willing to discuss any new input to ensure the quality and authenticity of olive oil.

For more information about the IOC, visit www.internationaloliveoil.org . To contact the Council by email, write to iooc@internationaloliveoil.org

UC Davis stands behind the report

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 (see www.olivecenter.ucdavis.edu), 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.