Evaluation of different storage conditions of extra virgin olive oils with an innovative recognition tool built by means of electronic nose and electronic tongue M.S. Cosio a, * , D. Ballabio a , S. Benedetti a , C. Gigliotti b a Department of Food Science and Technologies, University of Milan, Via Celoria 2, 20133 Milan, Italy b Department of Biomedical Sciences and Biotechnologies, University of Brescia, Viale Europa 11, 25123 Brescia, Italy Received 19 December 2005; accepted 6 February 2006 Abstract In the present work, the oxidation of extra virgin olive oils was considered at different storage periods and conditions. The oxidation is usually evaluated by applying an accelerated thermoxidation, while in this case real storage conditions were used. In order to study the differences of the storage situations, multivariate statistical analysis was applied on classical chemical determinations, electronic nose and electronic tongue responses. Results showed how the electronic nose was enough to define the extra virgin olive oil oxidation and appeared to be able to describe the different storage conditions, while classical chemical parameters and electronic tongue were not relevant. In fact, the classification model built by means of linear discriminant analysis (LDA) gave an equal classification performance by considering all the variables or just the electronic nose sensor responses. Compared to classical methods, this new approach could represent an alternative and inno- vative tool for faster and cheaper evaluation of extra virgin oil oxidation. Ó 2006 Elsevier Ltd. All rights reserved. Keywords: Extra virgin olive oil; Oxidation; Storage; Electronic nose; Electronic tongue; LDA 1. Introduction Extra virgin oil is properly processed from fresh and mature high quality olives (Olea europea L.) and presents a complex flavour which is greatly liked by native consum- ers and internationally appreciated by gourmets (Kiritsakis & Min, 1989). Flavour is usually divided into the subsets of aroma and taste, which are perceived in the nose and in the mouth, respectively. Many authors in fact have clearly demonstrated that the flavour is mainly produced by vola- tile and phenol compounds (Flath, Forrey, & Guadagni, 1973; Morales, Aparicio, & Rios, 1994), most of which have been identified and quantified in different extra virgin olive oils (Tsimidou, Papadopoulos, & Boskow, 1992; Vichi et al., 2003). Lipolysis and oxidation are the processes leading to the most serious deterioration of olive oil. Lipolysis usually starts when the oil is still in the fruit, while the oxidation begins at the processing stage and proceeds during storage influenced by exposition to air, heat, light and metals. Though extra virgin olive oil is considered to be a stable oil due to the presence of natural antioxidants, it is also susceptible to oxidation (Rovellini & Cortesi, 2002a). Vol- atile compounds are the main responsible of the pleasant flavour and change in off-flavours during the storage (Angerosa, Basti, & Vito, 1999; Morales, Rios, & Aparicio, 1997). At present the classical methods used to ascertain extra virgin olive oil quality are based on chemical analysis (Reg- ulation EEC/2568/91) and sensory analysis (Regulation 0308-8146/$ - see front matter Ó 2006 Elsevier Ltd. All rights reserved. doi:10.1016/j.foodchem.2006.02.005 * Corresponding author. Tel.: +39 2 5031 6623; fax: +39 2 5031 6632. E-mail address: stella.cosio@unimi.it (M.S. Cosio). www.elsevier.com/locate/foodchem Food Chemistry 101 (2007) 485–491 Food Chemistry