The Chemistry of Olive Oil: an endless story

Lanfranco Conte

doi:10.1051/ocl/2020024

Abstract

Because of their value, Olive oils, undergo to several attempts of adulteration and this improved the performances of analytical methods developed to check their authenticity. After the eve of the “Chemistry of indexes”, the development of separation techniques greatly improved the knowledge of the composition of lipids; the earlier gas chromatographic separations of fatty acid, could last even more than 40 minutes and the evaluation of minor fatty acids were problematic, at Bologna University, their previous separation on silver nitrate silica gel TLC was applied in 1974–1975, in order to concentrate them and obtain a better chromatogram. The gas chromatographic evaluation of minor compounds was another interesting challenge, packed columns with apolar stationary phase, admit the separation of few peaks; in 1975, the use of a slightly more polar stationary phase (OV17) highlighted the presence of Δ-5-avenasterol in olive oils. 1981 is a milestone for olive oil analytical control: Regulation (CEE) 2568/91 made the use of capillary columns mandatory. Official analytical methods consider many parameters, enclosed sensory evaluation, that is not matter for chemists, however, chemists are moved by curiosity and several papers had been published on the relationship between the volatile compounds of head space of olive oil and sensory characteristics. Despite being one of the more studied food, olive oils’ composition continues to give the chemists the possibility to discover new compounds, e.g. degradation products of sterols that leads to the standardization of the method for sterenes evaluation. From 1973 to nowadays, the laboratory performances greatly improved, nowadays it is possible to generate a huge number of data in a short time, then the problem is how to correctly interpretate them, surely chemometric and lipidomic greatly can help.

Highlights

The assessment of purity of foods had been an hot topic through the whole human history, the higher was the value of a food, the higher were the possibilities that is underwent to tentative of frauds; Romans greatly appreciated the olive oil produced in the Liburnia Region, but the delivery from that region to Rome was dangerous, so that they imported oils from Hispania Baetica, but a recipe was found describing how to add some flavors to this oil to sell it as a Liburnia’s one
Detector is used, An alternative detector is the Light Scattering, Conte et al used it in 1992 (Caboni et al, 1992) and fast analysis were possible, even if some doubts about the linearity were expressed (Fig. 8). This kind of detector was recently improved ad leads to the production of the CAD (Lucci et al, 2018), used a new ultra high-pressure liquid chromatography method using charged aerosol detector (UHPLC-CAD) with an inverse-gradient solvent compensation has been developed for the analysis of triacylglycerols (TAGs) in extra-virgin olive oil
The problem of contaminants: we studied the presence of PAHs through the production chain of all categories of oils extracted from olives, several contamination sources were identified and a rapid, simple and performing analytical method was developed for their determination, the method met the EEC required characteristic for PAHs evaluation method in fats and oils

Summary

Introduction

The assessment of purity of foods had been an hot topic through the whole human history, the higher was the value of a food, the higher were the possibilities that is underwent to tentative of frauds; Romans greatly appreciated the olive oil produced in the Liburnia Region (nowadays the area of Rjieka, Croatia), but the delivery from that region to Rome was dangerous, so that they imported oils from Hispania Baetica, but a recipe was found describing how to add some flavors to this oil to sell it as a Liburnia’s one. Detector is used, An alternative detector is the Light Scattering, Conte et al used it in 1992 (Caboni et al, 1992) and fast analysis were possible, even if some doubts about the linearity were expressed (Fig. 8) This kind of detector was recently improved ad leads to the production of the CAD (Lucci et al, 2018), used a new ultra high-pressure liquid chromatography method using charged aerosol detector (UHPLC-CAD) with an inverse-gradient solvent compensation has been developed for the analysis of triacylglycerols (TAGs) in extra-virgin olive oil. The official method form sensory evaluation of virgin olive oils, named “panel test”, uses the median value of selected characteristics detected by a group of sensory assessors, we

19 Heptanal

Conclusions