HPLC PROFILE AND EVOLUTION DURING STORAGE OF TRIGLYCERIDES AND DIGLYCERIDES IN VIRGIN OLIVE OILS

High-performance liquid chromatography has been used for determining the triglyceridice and diglyceridice composition of olive oils from main, minor and neglected Sicilians cultivars. The HPLC analysis has allowed the identification and the quantification of 16 triglycerides. Among these, OOO, POO+SOL, OOL and POL, have shown a content higher than 84% of the total area of peaks in the chromatographic profile. Dioleine (OO) and oleopalmitine (OP) resulted the most representative diglycerides. Analyses have been made in January 2007 and repeated after six months, submitting samples to a simulation of shelf life, to verify as the storage conditions may influence the hydrolitic processes of triglycerides, producing variations in the diglyceridic profile. The importance of study about the diglycerides is in fact to impute the correlation between the content in mono and diglycerides and the oxidative stability of oils. The experimentation has allowed to verify meaningful decrements in oleopalmitine (OP) content, while opposite course have shown the dipalmitine (PP), and the stearilpalmitine (SP). Principal component analysis (PCA), were applied to data of content of various triglycerides and diglycerides, to explore their capacity to discriminate varieties of olive oil, belonging to a Sicilian origin denomination. That statistic analysis permitted moreover to differentiate significantly samples in the two different storage periods.