Monitoring the bioactive compounds status of extra-virgin olive oil and storage by-products over the shelf life Jesus Lozano-Sánchez a, b , Alessandra Bendini c , Rosa Quirantes-Piné a, b , Lorenzo Cerretani c , Antonio Segura-Carretero a, b, * , Alberto Fernández-Gutiérrez a, b a Department of Analytical Chemistry, Faculty of Sciences, University of Granada, Fuentenueva s/n, E-18071 Granada, Spain b Functional Food Research and Development Center, Health Science Technological Park, Avenida del Conocimiento s/n, E-18100 Granada, Spain c Department of Food Science, Alma Mater Studiorum, University of Bologna, P.zza Goidanich 60, I-47521 Cesena, FC, Italy article info Article history: Received 20 April 2012 Received in revised form 20 June 2012 Accepted 21 June 2012 Keywords: Olive oil Storage by-products Polyphenols Half-life Elimination and appearance rate constants HPLCeESIeTOF-MS abstract The goal of this work was to monitor the phenolic profile of extra-virgin olive oil (EVOO) and of storage by-products in order to achieve a better understanding of the behaviour of these bioactive compounds during storage in the mill companies. Olive oil was stored in 1000-L tanks for 10 months. Qualitative and quantitative variations of the bioactive polyphenols over time were evaluated by high-performance liquid chromatography (HPLC) coupled to electrospray time-of-flight mass spectrometry (TOF-MS) method. Half-life, and elimination, and appearance rate constants (Kel and Ka, respectively) were established for the main phenolic compounds characterized in the samples. When the correlation for the pair oleuropein aglycone or decarboxymethyl oleuropein aglycon and their hydrolyzed derivatives was evaluated, the determination coefficients (r 2 ) were higher than 0.950. On the other hand, at all stages of the storage, by-products exhibited a higher hydroxytyrosol content than did olive oil because its Ka was higher in the by-products than in the olive oil. The results could have a dual application: to determine the freshness:ageing ratio of an extra-virgin olive oil, and to establish the optimal time for collecting the storage by-products as an alternative source of polyphenols with bioactive properties. Ó 2012 Elsevier Ltd. All rights reserved. 1. Introduction Extra-virgin olive oil (EVOO), the main Mediterranean dietary fat, is well-known for its health benefits (Kontou, Psaltopoulou, Panagiotakos, Dimopoulos, & Linos, 2011; Psaltopoulou, Kosti, Haidopoulos, Dimopoulos, & Panagiotakos, 2011). Early studies attributed these benefits to its monoinsaturated fatty acid content (Fernández-Jarne et al., 2002; Martínez-González et al., 2002). However, recent research indicates that minor constituents appear to prevent several diseases. Indeed, the juice derived from the first cold pressing of the olives without any further refining process, naturally contains high levels of phenolic compounds associated with the health benefits (Cicerale, Conlan, Sinclair, & Keast, 2009). These compounds exert strong antiproliferative effects on many pathological processes (Corona et al., 2009; Deiana et al., 2010; Incani et al., 2010), motivating the polyphenolic characterization of the different EVOO varieties (Lozano-Sanchez, Segura-Carretero, et al., 2010). Several high-performance analytical methods have been developed to characterize the complex phenolic pattern in EVOO. The main tool in characterization and quantitative analysis of phenolic compounds is liquid chromatography coupled with mass spectrometry using different kinds of mass spectrometers (De La Torre-Carbot et al., 2005; García-Villalba et al., 2010; Lozano- Sanchez, Segura-Carretero, et al., 2010; Suarez, Macia, Romero, & Motilva, 2008). Nevertheless, phenolic compounds present primarily in a fresh EVOO are characterized by a complex mixture of compounds belonging to different classes (simple and alcoholic phenols, secoiridoids, lignans and flavones). Furthermore, these compounds may generate derivatives during EVOO storage which have not been completely characterized. Given the importance of the phenolic fraction, regard to anti- oxidant activities (Bendini, Cerretani, Vecchi, Carrasco-Pancorbo, & Lercker, 2006), sensory properties (Esti, Contini, Moneta, & Sinesio, 2009) and health benefits (Bendini et al., 2007), the change in the phenolic compounds over time could be an important quality control parameter of EVOO. The main effects tested in the phenolic fraction during oil storage have been hydrolysis of secoiridoids and * Corresponding author. Department of Analytical Chemistry, Faculty of Sciences, University of Granada, Fuentenueva s/n, E-18071 Granada, Spain. Tel.: þ34 958249510; fax: þ34 9582495. E-mail address: ansegura@ugr.es (A. Segura-Carretero). Contents lists available at SciVerse ScienceDirect Food Control journal homepage: www.elsevier.com/locate/foodcont 0956-7135/$ e see front matter Ó 2012 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.foodcont.2012.06.036 Food Control 30 (2013) 606e615