EXECUTIVE SUMMARY
While there are many excellent imported and domestic extra virgin olive oils available in California, our findings
indicate that the quality level of the largest imported brand names is inconsistent at best, and that most of the topselling
olive oil brands we examined regularly failed to meet international standards for extra virgin olive oil.
In this second and final report in a year-long study, 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. The two laboratories
evaluated the oils based on standards and testing methods established by the International Olive Council (IOC) . The
laboratories also examined oils based on methods adopted in Germany and Australia. The labs evaluated oils in the
same manner as if the oils had been submitted by a private party seeking an evaluation. The average purchase price of
the top-selling imported brands was $0.47/ounce, the California brand was $0.46/ounce, Australian brand was
$0.42/ounce, and the top-selling premium Italian brand was $0.89/ounce.
In contrast to the first UC Davis report of July 2010, which analyzed 52 samples of 14 brands, this report’s aim was to
analyze fewer brands but more samples of each brand so as to improve the analysis 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. Sensory defects are indicators that these samples are
oxidized, of poor quality, and/or adulterated with cheaper refined oils.
• 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 ultraviolet absorption (UV) tests.
• 70 percent of the samples from the five top-selling imported brands failed the German/Australian 1,2-
diacylglycerol content (DAGs) test and 50 percent failed the German/Australian pyropheophytin (PPP) test. All
of the 18 samples of the California brand passed the DAGs test and 89 percent of the samples passed the PPP
test. The Italian premium brand failed the DAGs and PPP tests in about one-third of the samples. The
Australian brand passed the DAGs test in all cases and failed the PPP test in all cases.
• The strongest relationship between chemical analysis and negative sensory results was found in the DAGs test
(65 percent), followed by the PPP test (49 percent), UV K268 for conjugated trienes (34 percent), UV K232 for
conjugated dienes (12 percent) and UV ∆K (6 percent). The FFA, FAP and PV tests did not confirm negative
sensory results. The IOC standards would be more effective in assessing and enforcing olive oil quality by
including the DAGs and PPP standards.
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.
We recommend pursuing further research on the following topics: (1) investigate chemical markers of sensory defects,
(2) determine the effects of minor constituents on oxidative stability and flavor deterioration and (3) establish chemical
profiles of California olive oils.
INTRODUCTION
While there are many excellent imported and domestic extra virgin olive oils available in California, our findings
indicate that the quality level of the largest imported brand names is inconsistent at best, and that most of the topselling
olive oils we examined regularly failed to meet international standards for extra virgin olive oil.
“Extra virgin” is the top grade of olive oil according to standards established by the International Olive Council (IOC)
and the United States Department of Agriculture (USDA). In addition to establishing chemistry standards for extra
virgin olive oil, the IOC and USDA have established a sensory standard — the oil must have zero defects and greater
than zero fruitiness.
The IOC “is the world’s only international intergovernmental organisation in the field of olive oil and table olives. It was
set up in Madrid, Spain, in 1959, under the auspices of the United Nations.”1 The IOC’s duties include adopting
standards for industry, developing chemical and sensory testing methods to assess olive oil quality, and providing
official recognition to laboratories that demonstrate proficiency in employing the IOC’s recommended testing methods.2
Although the United States is not a member of the IOC, the USDA recently adopted3 olive oil standards that closely
correspond to the IOC standards.4 For simplicity, this report will reference the IOC standards and not the USDA
standards. The IOC olive oil standards include the grades of extra virgin, virgin, refined olive oil and “olive oil” (a
blend of virgin olive oil and refined olive oil).
In July 2010 the UC Davis Olive Center issued a report showing that 69 percent of imported olive oils labeled as “extra
virgin” failed the IOC sensory standard - in other words, these oils were defective and failed to meet the international
standard for extra virgin olive oil. In the months since the release of the study, similar quality problems have been
found in Andalusia, the world’s most productive olive oil region, by Spanish authorities.5
In this second and final report of a year-long study, 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. UC Davis and the
Australian laboratory evaluated the oils based on standards and testing methods established by the IOC. Additionally,
the two laboratories analyzed the oils using two testing methods adopted in Germany and Australia. The Australian
Olive Association adopted these tests to help detect extra virgin olive oils that were old and oxidized and not up to
extra virgin olive oil standards.
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, all purchased in California. In contrast, the IOC’s quality control program assessed an average of 116
extra virgin olive oil samples per year purchased in the entire United States and Canada in the 2008-2009 period.6
The UC Davis studies offer a statistically significant picture of extra virgin olive oil quality sold in California, the mostpopulous
state in the world’s third-largest olive oil consuming nation.
METHODOLOGY
Testing methods. The UC Davis and Australian laboratories examined oils in the same manner as if the oils had been
submitted by a private party seeking an evaluation. The analytical methods used in this study, summarized in Table 1,
include the chemistry and sensory testing methods adopted by the IOC. While not all of the IOC chemical tests were
included in this study, the primary tests used by producers worldwide - free fatty acids (FFA), peroxide value (PV), ultraviolet absorption (UV), fatty acid profile (FAP) and sensory, were included. The UV tests were particularly useful in our July 2010 study. The study also employed supplementary standards that have been adopted by the German government and the Australian Olive Association (AOA) as useful tools to assess olive oil quality.
1 International Olive Council (IOC) website (http://www.internationaloliveoil.org/), English version, viewed February 5, 2011.
2 See IOC COI/T.15/NC No 3/Rev. 5 November 2010 for olive oils standards; IOC COI/OT/NC No. 1-December 2004 for table olives standards;; Table 1 of this report
for chemistry and sensory testing methods; and http://www.internationaloliveoil.org/estaticos/view/226-laboratories-panels regarding IOC recognition of chemical and
sensory testing laboratories.
3 See USDA, “United States Standards for Grades of Olive Oil and Olive-Pomace Oil,” Federal Register, April 28, 2010.
4 There are some differences between the IOC and USDA standards, such as allowable limits for campesterol in the grade of extra virgin olive oil and median panel scores
for defects in the grade of virgin olive oil.
5 See Olive Oil Times, December 5, 2010.
6 See International Olive Council, CONV./R.36/Doc. No 2, October 2009.
For continuation of report dated April 2011, see:
http://olivecenter.ucdavis.edu/research/files/report041211finalreduced.pdf
See also: Fake Olive Oil Companies Revealed – Stop Buying These Brands Now!
