Influence of horizontal centrifugation processes on the content of phenolic secoiridoids and their oxidized derivatives in commercial olive oils: an insight by liquid chromatography - high resolution mass spectrometry and chemometrics.

Reversed-phase liquid chromatography with electrospray ionization-high resolution/accuracy Fourier-transform mass spectrometry (RPC-ESI-FTMS) and chemometrics were exploited to evaluate the influence of horizontal centrifugation by two- or three-phase decanters on the content of major phenolic secoiridoids in extra-virgin olive oils (EVOOs). Despite the occurrence of other potential sources of variability typical of commercial olive oils, horizontal centrifugation was found to play a primary role, with a general increase of secoiridoids content occurring when two-phase decanters were used. As emphasized by Principal Component Analysis (PCA), the increase involved preferentially oleacin and oleocanthal, when oxidative deterioration was purposely minimized during and/or after production, and oleuropein and ligstroside aglycones, when no vertical centrifugation was performed at the end of the productive cycle. The influence of the type of horizontal centrifugation was emphasized also by the elaboration of RPC-ESI-FTMS data based on Hierarchical Cluster Analysis (HCA) and Linear Discriminating Analysis (LDA).