The food fight over the purity of extra virgin olive oil has boiled up again.
The UC Davis Olive Center and the Australian Oils Research Laboratory released on Wednesday a second research report that found nearly three-quarters of the samples they tested of top-selling imported olive oil brands failed international extra virgin standards.
The report follows a similar study the two research centers conducted last summer, which slammed imported olive oils and said that two-thirds of common brands of extra-virgin olive oil found in California grocery stores aren't what they claim to be.
Wednesday's report, entitled "Evaluation of Extra-Virgin Olive Oil Sold in California," drew a larger group of samples from fewer brands ?- done in part to address some of the criticisms of the research methodologies used in last year's report.
The brands tested in this recent report were Filippo Berio, Bertolli, Pompeian, Colavita and Star. The researchers also tested samples of the top-selling premium Italian brand Lucini; Cobram Estate, the largest Australian olive oil producer; and California Olive Ranch, the leading U.S. producer.
California Olive Ranch helped fund the study.
Last September and October, UC Davis researchers said they went to retailers in Northern, Central and Southern California, and bought bottles labeled as 100% extra-virgin olive oil from both domestic and imported producers.
According to the report, researchers found that 73% of the 134 samples from the eight producers failed the sensory ?- or taste and smell ?- tests established by the International Olive Council (IOC).
In addition, the report stated the imported and domestic samples were run through seven chemical laboratory tests. Seventy percent of the imports failed one particular test. Fifty percent failed another test and some of the samples failed five out of the seven chemical laboratory tests. . . . Researchers said only 11% of the California-produced samples failed one test. The rest of those samples passed all of the chemical tests, as well as the sensory tests.
"This confirms what we found in the first report. Now, there are two reports and quite a bit of consistency," said Dan Flynn, executive director of the UC Davis Olive Center.
The IOC, whose members make up 97% of the global production of olive oil, were less convinced. In a statement released Wednesday, the Spanish-based organization accused both reports of having "the same evident undercurrent of aggressive, inexplicable criticism of imported olive oil quality."
Industry officials generally agree that the "extra-virgin" designation is proper for oil that is cold-processed to prevent degradation of aromatic compounds and has higher levels of healthful fats and antioxidants. It also has relatively low acidity levels -- 0.8 grams per 100 grams or less, according to the international group.
The purity issue is a serious concern for some consumers. Some state agencies previously uncovered oils labeled as 100% extra-virgin olive oil that were blended with cheaper canola, seed or nut oils -- a significant health threat to people with allergies. (No such mixing of nut oils was found in either last year's tests or the recent tests of products sold in California, according to the report.) Money is also at stake, as extra-virgin oil is often sold as a premium-priced product.
Yet consistently replicating the researchers' findings has proved to be challenging to a California legal team that was leading a class-action lawsuit over the purity of imported olive oil.
Last August, a group of chefs, restaurants and others filed a complaint in Orange County Superior Court claiming that several retailers and olive oil producers had misled Californians about the actual quality of the olive oil they sold.
But plaintiff attorney Daniel J. Callahan said his firm ran into difficulties when it sent olive oil samples to various laboratories for testing: The results, he said, were inconsistent.
"There were good grades in Georgia, but bad in California," Callahan said on Wednesday. "It wasn't consistent enough to meet the profile of the kind of case" his firm handles.
The class-action complaint was dropped last month, Callahan said.