ORIGINAL ARTICLE Investigation of the Effects of Virgin Olive Oil Cleaning Systems on the Secoiridoid Aglycone Content Using High Performance Liquid Chromatography–Mass Spectrometry Raffaella Pascale 1 · Giuliana Bianco 2 · Tommaso R. I. Cataldi 3 · Alessandro Buchicchio 1 · Ilario Losito 3 · Giuseppe Altieri 4 · Francesco Genovese 4 · Antonella Tauriello 4 · Giovanni C. Di Renzo 4 · Maria C. Lafiosca 2 Received: 11 April 2017 / Revised: 15 March 2018 / Accepted: 28 March 2018 © 2018 AOCS Abstract Phenolic compounds are useful markers to con- trol olive oil technological processes, including the virgin olive oil (VOO)/water separation after olive oil extraction. In this investigation, VOO extracted from olives of cv. Coratina using a mild oil/water separator called the hydrocyclone sedi- mentation system (Hydroil) was compared with VOO obtained using a conventional vertical centrifuge separator (Cenoil), which is mostly used in the modern olive oil indus- try. Secoiridoid aglycones were selected, among phenolic compounds, as markers and analyzed using reversed-phase liquid chromatography coupled to linear quadrupole ion-trap mass spectrometry with electrospray ionization in the nega- tive mode. VOO samples obtained using the Hydroil system were found to contain significantly higher levels of secoiri- doid aglycones, compared to the Cenoyl-type samples. In par- ticular, the total content of the aglycones of decarboxymethyl oleuropein, decarboxymethyl ligstroside, ligstroside, and oleuropein, expressed in terms of oleuropein, was estimated as 35.40  0.80 mg kg -1 , compared to 8.06  0.41 mg kg -1 in the Cenoil samples (n = 3). Since no significant difference in residual water (P < 0.05) was found between the two types of VOO samples, the higher amount of secoiridoids obtained for Hydroil-type ones was explained by the lower extent of oxidation occurring during the mild oil/water separation achieved using the Hydroil system. Keywords Secoiridoids  Virgin olive oil  Hydrocyclone  Liquid chromatography  Mass spectrometry J Am Oil Chem Soc (2018). Introduction Over the last few decades, the quality control of virgin olive oil (VOO) has become an important issue during olive oil pro- duction and processing (Di Giovacchino, Sestili, & Di Vin- cenzo, 2002; Veneziani et al., 2016), which could strongly affect the antioxidant activity of VOO phenolic components. The main hydrophilic phenols with high biological activity occurring in olive fruits are secoiridoid aglycones, generated during the olive oil extraction process by the enzymatic hydro- lysis of the oleuropein and ligstroside glucosides, accompanied by further enzymatic processes, leading to the corresponding decarboxymethylated forms (Kelebek, Selli, & Kola, 2017; Servili et al., 2004). The oil production steps also cause a par- tial modification of the cited aglycones, due to the keto-enolic tautomeric equilibrium that involves the ring opening of secoiridoids (Servili et al., 2004). The generated isoforms of secoiridoids retain the phenolic moiety, thus preserving their antioxidant activities. Therefore, quantification of the derived secoiridoid aglycones in edible oils is significant for evaluating Electronic supplementary material The online version of this article (doi:10.1002/aocs.12072) contains supplementary material, which is available to authorized users. * Giuliana Bianco giuliana.bianco@unibas.it 1 Scuola di Ingegneria, Università degli Studi della Basilicata, via dell’Ateneo Lucano, 10-85100, Potenza, Italy 2 Dipartimento di Scienze, Università degli Studi della Basilicata, via dell’Ateneo Lucano, 10-85100, Potenza, Italy 3 Dipartimento di Chimica, Università degli Studi di Bari Aldo Moro, Via E. Orabona, 4-70126, Bari, Italy 4 Scuola di Scienze Agrarie, Forestali, Alimentari ed Ambientali, Università degli Studi della Basilicata, via dell’Ateneo Lucano, 10-85100, Potenza, Italy J Am Oil Chem Soc (2018) DOI 10.1002/aocs.12072 J Am Oil Chem Soc (2018)