The UC Davis Olive Center evaluated 21 olive oil samples sold to the restaurant and foodservice sectors based on the voluntary standards of the United States Department of Agriculture (USDA) and tests that have been adopted by the International Organization for Standardization (ISO). Our analysis found that:
• All but one of the 15 “extra virgin” samples passed the most commonly used USDA chemistry standards (free fatty acidity, peroxide value, and ultraviolet absorbence) to test quality;
• Despite this high passage rate, 60 percent of the samples failed the USDA “extra virgin” sensory standard, which is a standard rarely used for quality-control purposes in the foodservice and restaurant sectors. Some of the oils were so defective that they were classified by sensory panels as “not fit for human consumption” under the USDA standard;
• All of the “extra virgin” samples that failed the USDA sensory standard also failed the diacylglycerol (DAGs) standard adopted by the Australian Olive Association (AOA);
• Six of nine of the “extra virgin” samples that failed the USDA sensory standard also failed the pyropheophytin (PPP) standard adopted by the AOA;
• Chemical purity tests indicated that one of 15 “extra virgin” samples and one of six “olive oil” samples were adulterated with inexpensive canola oil.
We recommend: further research using a larger sample size than that used in this study; that the USDA revise extra virgin standards to include the DAGs and PPP tests; that food distributors augment their quality control protocols with the sensory, DAGs, and PPP tests; further research to develop tests that are faster, better and cheaper than the tests currently available; and further research on innovative packaging to extend olive oil freshness.
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