Olive oil triglycerides separation by HPLC and on-line DAD and RID detection: a contribution to identify extra virgin oil blends with soft-deodorised olive oils

Extra virgin olive oil is one of the healthiest vegetable oils and it is the best source of fats in the Mediterranean Diet. Olive tree cultivation and olive oil consumption spread all over the world and since extra virgin olive oil is also one of the most expensive oils, often undergoes fraudulent practices by mixing it with lower grade oils. Improved knowledge of olive oils and technology may give rise to a frequent extra virgin counterfeiting by mixing authentic extra virgin olive oils with the so-called soft- or mild-deodorised oils: these are virgin oils, deodorised in a soft way to distillate unpleasant compounds so that oils can be blended with real extra virgin oils and be illegally sold as if they were fully authentic. The aim of this paper is to describe an approach that takes into consideration the ultraviolet absorbency of each triglyceride in soft-deodorised oils or micro- or ultra-filtered oils and their blends with authentic extra virgin oils. Further data elaboration by principal component analysis allowed us to clearly distinguish false extra virgin oils from authentic. Furthermore, chromatographic separation enables us to calculate the ECN42 without performing a new HPLC separation according to the Official method, as required by the law in force.