Despite the great efforts devoted to the study of the chemical composition of olive oil, the identification of minor components is still incomplete. Within this context, the characterization of esters of fatty alcohols with fatty acids is far from complete. The objective of this study is to investigate phytyl wax esters profile of extra-virgin olive oils, in order to provide an update on the current knowledge of the chemical composition of this fraction. Extra-virgin olive oil waxes are transesterificated with HCl/isobutanol and isobutyl esters are analyzed by GC-FID and GC-MS using two capillary columns with different polarity. A comparison of the GC retention times with analytical standards together with the acquired mass spectra allow to identify and confirm, for the first time, phytyl vaccinate as the relevant unknown peak detected in the wax esters fraction of extra-virgin olive oils. Additionally, the analysis of the composition of aliphatic alcohols obtained by hydrolysis of waxes reveals that
the preponderant compound is C24 alcohol derived from lignoceryl palmitate, which is practically the only wax really present, while the low level of C28 alcohol confirms that extra-virgin olive oils of good quality contain negligible amounts of long-chain waxes which are derived from C28 alcohol.
Practical Applications: Phytil vaccinate has been shown for the first time as a relevant component of apolar olive oil fraction, highlighting the importance of studying the biosynthesis of the esterified apolar fraction of extra virgin olive oils since acids esterified with diterpenes are quantitatively different from those found in triglycerides. From a nutritional point of view, the identification and characterization of the diterpenic esters profiles of the apolar fraction of extra virgin olive oils is of particular interest, especially considering that these compounds contribute to the reduction of blood cholesterol levels.
