Evaluation of Extra-Virgin Olive Oil Sold in California

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Evaluation of Extra-Virgin Olive Oil Sold in California

Frankel, E.N.; Mailer, R.J.; Wang, S.C.; Shoemaker, C.F.; Guinard, J.-X.; Flynn, J.D.; Sturzenberger, N.D.


In this second report, UC Davis again worked with the Australian Oils Research Laboratory to evaluate the quality of extra virgin olive oils sold on retail shelves in California. In contrast to the first UC Davis report on July 2010, which analyzed 52 samples of 14 brands, this report’s aim was to analyze fewer brands but more samples of each brand. In addition, this study used two IOC-accredited sensory panels to conduct analysis based on the IOC sensory standards for extra virgin olive oil, in contrast to the July study, which used a single sensory panel to analyze samples. With this study and the July 2010 study, the research team has analyzed a total of 186 extra virgin olive oil samples in the past year, offering a statistically significant picture of olive oil quality sold in California, the most-populous state in the world’s third-largest olive oil consuming nation. Among the findings:

-          Of the five top-selling imported ‘extra virgin’ olive oil brands in the United States, 73 percent of the samples failed the IOC sensory standards for extra virgin olive oils analyzed by two IOC-accredited sensory panels. The failure rate ranged from a high of 94 percent to a low of 56 percent depending on the brand and the panel. None of the Australian and California samples failed both sensory panels, while 11 percent of the top-selling premium Italian brand, samples failed the two panels.

-          All of the oil samples passed the IOC chemistry standards for free fatty acids (FFA), fatty acid profile (FAP) and peroxide value (PV), but several of the imported samples failed the IOC’s unltraviolet absorption (UV) tests.

Our testing indicated that the samples failed extra virgin olive oil standards according to one or more of the following: (a) oxidation by exposure to elevated temperatures, light, and/or aging; (b) adulteration with cheaper refined olive oil; and (c) poor quality oil made from damaged and overripe olives, processing flaws, and/or improper oil storage.