IOC grading standards require that extra virgin olive oil be free of sensory defects and have some positive sensory attributes, traits which, to date, can only be judged by a tasting panel. Therefore the IOC requires sensory, or panel, testing to assess oil as being virgin or extra virgin grade.
With this method, a panel of human evaluators record their sensory responses to the products being tested.
Statistical analysis is then employed to generate inferences and insights regarding the product.a An olive oil that meets all chemical standards for the extra virgin grade can still fail to make the grade if a certified sensory panel finds that the positive sensory attributes are absent and/or a defect is present.
The IOC provides written sensory evaluation standards for olive oil, including definitions of sensory properties and defects and a point system for assigning grades or classifications; it also prescribes methods of panel training and certifies laboratories evaluating olive oil.
In a panel test, a group of 8 to 12 trained panel testers taste and evaluate the olive oils in testing rooms. The IOC recommends that a maximum of four olive oil samples be evaluated in each session, with a maximum of three sessions per day, per tester, to avoid tasting fatigue.
In addition, palates should be cleansed between samples and a minimum of 15 minutes should elapse between sessions. Given these time requirements and the time and cost needed to train a panel tester, sensory panel testing can be a bottleneck, especially in view of the vast amount of virgin and extra virgin olive oil that is globally traded and marketed.