When it comes to olive oil, it seems as though the nose and taste buds can do a better job evaluating quality than U.S. chemical tests.
The University of California, Davis, conducted a study that found that some olive oils sold to the food industry were described as “lamp oil” or were diluted with cheaper oil, such as canola, yet passed federal chemistry tests. Based on the study’s findings, the university recommended that restaurant and food-service sectors enhance their quality-control protocols for olive oil by including more effective tests outlined in the report, reports Futurity.
“Results of this study make it very clear that efforts to control the quality of olive oils served in restaurants and other food-service operations will likely fail if they are based only on the most commonly used chemical analyses,” says Dan Flynn, executive director of the UC Davis Olive Center and a co-author of the study. “It is now clear that even olive oils that prove to be substandard according to sensory tests can slip past existing chemical protocols.”
The researchers tested 21 olive oil brands sold to restaurants and food-service establishments, 15 of which were labeled as “extra virgin,” the highest-quality grade for olive oil. The other six olive oil samples were not labeled. All of the samples were sent to the Australian National Oils Laboratory for sensory and chemical testing. The samples also went to sensory panels in Spain and Italy.
The analyses occurred as blind tests, in which the laboratory testers and the sensory reviewers did not know the brand name or country of origin of the olive oil samples. Here are some of the results:
- Fourteen of the 15 extra virgin olive oils passed commonly used U.S. chemistry standards for quality. However, nine, or 60%, of the samples failed sensory standards for extra virgin, criteria that are rarely used by food distributors for quality control. Those nine oils also failed to pass chemical tests for the compound diacylglycerol, which is a standard used by the Australian Olive Association for extra virgin.
- The sensory reviewers often described the flavor and aromas of the oils as rancid, fusty or muddy, and musty. The sensory testers disliked some of the oils so much and thought them defective that they classified them as “lamp oil,” considered by U.S. standards to be unfit for human consumption without further refining.
- One of the 15 extra virgin samples and one of the six samples not labeled had been diluted with cheaper, refined canola oil, chemical tests showed. The researchers believe that the findings show a need for the United States to develop faster, more accurate, and less expensive tests, and to develop better packaging so that olive oil can stay fresher longer.
Dale McGeehon has been a journalist and editor for more than 25 years, covering chemical regulation and testing for Pesticides and Toxic Chemical News and innovations in material sciences for the National Technology Transfer Center. His writing credits include Omni and College Park magazines and The New York Times.