Non-conventional Parameters for Quality Evaluation of Refined Olive Oil and Olive Oil Commercial Classes

The analytical parameters to ascertain olive oil quality and classify olive oils are defined by the EC Regulation No 1989/2003. A table demonstrates that hydrolytic degradation is assessed by the percent free fatty acids (FFA); although this analysis is very useful and effective to attribute the commercial class to olive oils, it is not sufficient to define oil quality. Oxidative degradation is measured by the peroxide value (PV) and UV spectrophotometry. These analyses, however, take into account only few partial aspects of the complex phenomenon and do not meet the major need to know the actual state of oil oxidation based on the initiation, propagation and termination of the radical mechanism. This is even more relevant when one has to assess the quality of freshly refined oils. In such types of oils the percent FFA is not a reliable index, as FFA are removed during neutralization; nor is the determination of the PV viable because hydroperoxides are degraded and/or transformed by refinement, so that a freshly processed oil has a PV equal or very close to zero; this means that primary oxidation cannot be ascertained any longer by the PV. The use of plants' technological innovations would also influence these determinations. It seems thus necessary to have reliable analytical parameters for a more realistic assessment of quality. Reliable results have been obtained by the separation from oil of polar compounds (PC), which are constituted by substances having higher polarity than unaltered triglycerides. The subsequent HPSEC analysis of PC enables quantifying the following classes of substances: triglyceride oligopolymers (TGP), oxidized triglycerides (ox-TG), diglycerides (DG), sterols and triterpene diols, and FFA. © 2010 Copyright © 2010 Elsevier Inc. All rights reserved.