`Davis Olive Center Responds to IOC Criticism of Report - Olive Oil Times

Davis Olive Center Responds to IOC Criticism of Report

Feb. 22, 2011
Lori Zanteson

Recent News

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.

The 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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