Analytical Methods Discrimination of five Tunisian cultivars by Mid InfraRed spectroscopy combined with chemometric analyses of olive Olea europaea leaves Fathia Aouidi a,c,⇑ , Nathalie Dupuy b , Jacques Artaud b , Sevastianos Roussos c , Monji Msallem d , Isabelle Perraud-Gaime c , Moktar Hamdi a a Laboratory of Microbial Ecology and Technology, Department of Biological and Chemical Engineering, National Institute of Applied Sciences and Technology (INSAT), Centre Urbain Nord, 2 Boulevard de la Terre, B.P. 676, 1080 Tunis, Tunisia b ISM 2 , UMR 6263, Equipe AD 2 EM, Groupe systèmes chimiques complexes, Faculté des Sciences et Technique Saint Jérôme – Université Paul Cézanne, 13397 Marseille Cedex 20, France c IMEP UMR CNRS 6116/IRD UMR 193, Faculté des Sciences et Technique Saint Jérôme – Université Paul Cézanne, 13397 Marseille Cedex 20, France d Institut de l’olivier, B.P. 208, 1082 Tunis, Tunisia article info Article history: Received 13 December 2010 Received in revised form 7 March 2011 Accepted 17 August 2011 Available online 23 August 2011 Keywords: Olive (Olea europaea) leaf ATR-Mid InfraRed spectroscopy Chemometric analysis Cultivar Discrimination Chemical fingerprint abstract The high biodiversity of olive tree and the economic needs require tools for the correct classification and identification of the different cultivars. Simple and rapid methods are in increasing demand. In the pres- ent work, FT-MIR spectroscopy associated to chemometric treatment is proposed as a direct and rapid tool to discriminate cultivars according to their olive leaves, a persistent tissue the whole year. A set of 75 samples of olive leaves representative of five Tunisian cultivars (Chemlali, Sayali, Meski, Zarrazi and Chétoui) cultivated in the same geographical area was analysed. Discrimination between the five Tunisian cultivars was performed by the chemometric approach, principal component analysis (PCA), based on the FT-MIR spectral data provided by olive leaves. Furthermore, a correct classification (100%) of the five Tunisian cultivars was obtained by the Partial Least Square Discriminate Analysis (PLS-DA) method. Ó 2011 Elsevier Ltd. All rights reserved. 1. Introduction It is well known that qualitative and quantitative aspects of the production of olive oils and table olives vary, among others, with the cultivars (Gómez-Rico, Fregapane, & Salvador, 2008; Hannachi et al., 2008; Pinheiro & Esteves da Silva, 2005). Nowadays, the iden- tification of the olive cultivar become a topic of great economic rel- evance since the demand of table olives and olive oils is increasing and there is a growing commercial interest in high quality prod- ucts. Furthermore, correct cultivar identification can represent a useful tool for nursery owners who need to certify and patent their plant material. Until recently, olive cultivars are especially discriminated and classified on the base of morphological and agronomic characteris- tics (Pinheiro & Esteves da Silva, 2005; Trigui & Msallem, 2002). Identification based on the analysis of isoenzymes has also been ci- ted (Trujillo, Rallo, & Arus, 1995). Although these markers provide useful tools for cultivar identification, their actual limits are the small number of detected polymorphisms and the influence of envi- ronment and of olive growing techniques. The recent development of DNA molecular markers has led to the emergence of new genetic markers for identifying olive cultivars. Molecular markers, such as Simple Sequence Repeat (SSR) (Alba, Montemurro, Sabetta, Pasqu- alone, & Blanco, 2009; Bracci et al., 2009; Doveri et al., 2008; Hann- achi et al., 2008), Random Amplified Polymorphic DNA (RADP) (Zitoun et al., 2008) and Amplified Fragment Length Polymorphism (AFLP) (Belaj, Rallo, Trujillo, & Baldoni, 2004), are environment- independent and efficient to identify olive varieties. Recently, a chemometric approach based on the analytical data has been devel- oped for discrimination and classification of olive cultivars. Analyses were carried out on a particular olive tissue such as leaves (Di Donna et al., 2010; Japón-Luján, Ruiz-Jimnez, & Luque de Castro, 2006) or olive fruits (Casale et al., 2010; Dupuy et al., 2010) or on olive oil (Casale, Sinelli, Oliveri, Di Egidio, & Lanteri, 2010; Dupuy, Galtier, Ollivier, Vanloot, & Artaud, 2010; Sinelli et al., 2010). The discrimina- tion between varieties of olives trees cultivated in the same geo- graphical area can be performed by chemotaxonomic markers, such as secondary metabolites of phenolic structure identified by high performance liquid chromatography/electrospray ionisation tandem mass spectroscopy (HPLC–ESI-MS) (Di Donna et al., 2010), peak areas from a high performance liquid chromatography-diode array (HPLC–DAD) analysis of biophenols (Japón-Luján et al., 0308-8146/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.foodchem.2011.08.041 ⇑ Corresponding author at: Laboratory of Microbial Ecology and Technology, Department of Biological and Chemical Engineering, National Institute of Applied Sciences and Technology (INSAT), Centre Urbain Nord, 2 Boulevard de la Terre, University of Carthage, B.P. 676, 1080 Tunis, Tunisia. Tel.: +216 98 326 675. E-mail address: aouidifathia@yahoo.fr (F. Aouidi). Food Chemistry 131 (2012) 360–366 Contents lists available at SciVerse ScienceDirect Food Chemistry journal homepage: www.elsevier.com/locate/foodchem