Journal of Chromatography A, 1023 (2004) 271–276 Direct thermal extraction and gas chromatographic–mass spectrometric determination of volatile compounds of extra-virgin olive oils Paola Zunin a,∗ , Raffaella Boggia a , Silvia Lanteri a , Riccardo Leardi a , Roberto De Andreis b , Filippo Evangelisti a a Dipartimento di Chimica e Tecnologie Farmaceutiche e Alimentari, Università di Genova, Via Brigata Salerno (ponte), I-16147 Genova, Italy b Presidente Commissione Degustazione Olio Extra Vergine di Oliva DOP “Riviera Ligure” Regione Liguria–Via Fieschi, Genova, Italy Received 26 May 2003; received in revised form 12 September 2003; accepted 13 October 2003 Abstract The instrumental performances of a Thermo Desorption-Cooled Injection System coupled with a gas chromatography–mass spectrometer (GC–MS) were improved by a Plackett-Burman experimental design for the direct thermal extraction of volatile compounds from extra-virgin olive oils. The obtained experimental conditions were applied to the analysis of samples from West Liguria (cv. Taggiasca ≥90%) and Spain (cv. Arbequina), which shared such similar sensorial features that Taste Panel did not distinguish them. Principal component analysis (PCA) was then applied to the experimental data. Three linear combinations of the amounts of the lipoxygenase oxidation products proved to be decisive and sufficient in the differentiation of the two groups of samples. © 2003 Elsevier B.V. All rights reserved. Keywords: Olive oil; Direct thermal extraction; Principal component analysis; Plackett–Burman design; Lipoxygenase oxidation products; Volatile organic compounds 1. Introduction Extra-virgin olive oils are extracted from the fruit of olive tree, Olea europea, and are consumed without any refining process. Thus, they retain their volatile compounds, which are often present at extremely low concentrations but are responsible for their fragrant flavor and aroma [1]. Gas chromatography–mass spectrometry (GC–MS) has been widely used for the instrumental analysis of olive oil flavor. The preliminary extraction of volatiles from oils has been frequently obtained by dynamic headspace techniques, generally employing Tenax ® or Charcoal as adsorbents [2–4]. Some authors have also proposed an extraction by Solid Phase Micro Extraction (SPME) with polydimethylsi- loxane fibers, in order to detect polyunsaturated aldehydes that might be underestimated by Tenax ® [4], or by Supercrit- ical Fluid Extraction (SFE) followed by Tenax ® trapping [5]. In the late 90’s, Gerstel proposed the Thermo Desorption- Cooled Injection System TDS2-CIS4 for the extraction of volatiles or semi-volatiles from stir bars coated with the ∗ Corresponding author. Fax: +39-010-353-2684. E-mail address: zunin@dictfa.unige.it (P. Zunin). sorbent polydimethylsiloxane (PDMS). Nevertheless, the manufacturer itself proposed also the use of TDS2-CIS4 for the direct flavor extraction of olive oils and rancidity monitoring [6]: the employed analytical method avoided the use of stir bars and of any adsorbent, that might modify the ratios among the volatiles content. This approach has been considered particularly interesting and potentially useful for discrimination among olive oils showing similar organolep- tic features. Thus, in this study the TDS2-CIS4 system coupled with GC–MS was used for the direct extraction and analysis of the volatiles of two groups of extra-virgin olive oils: these oils had been obtained from different olive culti- vars in different geographical areas but had such similar sen- sorial features that the Taste Panel did not distinguish them. Since these oils had a delicate and light flavor, experimental conditions had to be improved and an experimental design was carried out in order to enhance method sensitivity. The resulting settings were then applied to the analysis of Italian “Riviera Ligure-Riviera dei Fiori” Protected Designation of Origin (PDO) [7] oils and of Spanish extra-virgin olive oils of the same year crop (2001–2002) obtained from cv. Ar- bequina. The chemical composition of the volatile fraction of the samples was examined and the obtained data were 0021-9673/$ – see front matter © 2003 Elsevier B.V. All rights reserved. doi:10.1016/j.chroma.2003.10.035