Olive oil mixtures. Part one: Decisional trees or how to verify the olive oil percentage in declared blends

The commercialization of declared blends of olive oil and seed oil is something long approved by the European Union. There, the olive oil percentage must be at least 50% if the producer aims to advertise its presence on the front label, i.e., somewhere other than in the ingredients list. However, the Regulation did not propose any method to verify such proportion. For this purpose, we recommend the use of decisional trees, being the parameters under study those in which the greatest differences between olive and seed oils are shown: triacylglycerols, acyclic saturated hydrocarbons, free sterols, and tocopherols. In this way, to guarantee the presence of olive oil at 50%: i) palmitodiolein must be above 11–15%; ii) the ß/γ-tocopherol ratio must be below 2.4; iii) the alkane sum C21-C25 should be higher than 3.5–6%; and iv) the total sterol content cannot surpass 2400 mg/ kg.