Olive oil analysis received more than its fifteen minutes of fame at this year’s annual meeting of the American Oil Chemists’ Society (AOCS) 30 April to 2 May in Long Beach, California. The weekend before the meeting there was a short course entitled Olive Oil Chemistry and Sensory Relationships, and Tuesday morning featured a technical group meeting and a session “Olive and Specialty Oil.”
Andy Proctor of the University of Arkansas introduced Rod Mailer of the Australian Oils Research Laboratory who started the olive oil short course with an overview of olive oil standards around the world. Standards have many benefits: they provide merchants and consumers the assurance of authenticity, safety and freshness, and they give producers a clear target for production.
But the current situation is anything but clear, with a mix of standards and methods originating from both international bodies—such as International Olive Council (IOC), Codex Alimentarius and the European Committee for Standardization (CEN)—and from national governments motivated by dissatisfaction with the current environment. Mailer suggests Codex Alimentarius, a program charged both with protecting consumer health and promoting fair trade practices, as the logical body to set international standards for olive oil.
Angela Sheridan of the Canadian Food Inspection Agency (CFIA) gave a presentation about the work being done in Canada to inspect olive oil. In the service of their mandate to protect consumers against product misrepresentation and fraud, the CFIA conducts targeted sampling and analysis of olive oils using the IOC standards. The program is concerned primarily with adulteration. The percentage of samples judged unsatisfactory has ranged from 47 percent in 2006-7 to 11 percent in 2009-10. It was an encouraging story, showing what happens when a government is willing to create a focused program and allocate funding to the objective.
One of the recurring themes of the standards discussion was the problem of chemical profiles that are based on a particular region. The profile of an olive oil will vary tremendously depending on the olive variety used and the climate where the olives are grown. A classic example of this is are the campesterol and Δ7 stigmastenol levels of Israeli oils made from the Barnea variety. These oils will regularly fall outside the IOC limits for those fatty acids and sterols.
Such natural variation in olive oil has led to some of these levels being set differently in national standards; the campesterol limit is ≤ 4.5 in the USDA standard, for example, instead of the ≤ 4.0 of the IOC standard. Mailer points out that the variability of the chemical profile of olive oil from places like Australia can be huge, since their olive growing region extends from the tropical to the cool temperate.
Whereas the sterols and fatty acid profile of an olive oil are examined to assure authenticity, other tests are aimed at assessing quality and freshness. The free fatty acid level, peroxide value and UV absorbency are the traditional tests used for this purpose. During the short course there was extensive discussion of two other tests that have been in use in the Northern European olive oil trade since at least 2006 and are incorporated into the recently adopted Australian standard for olive oil: pyropheophytin (PPP) and diacylglycerols (DAGs).
Support for the use of PPP and DAGs as indicators of olive oil age and quality was presented by Claudia Guillaume of the Modern Olives laboratory in Australia in the form of findings from three years of research on olive oil storage and quality assessment.