GC–MS–olfactometric characterization of the key aroma compounds in Turkish olive oils by application of the aroma extract dilution analysis Songul Kesen a , Hasim Kelebek b , Kemal Sen c , Mehmet Ulas d , Serkan Selli e, ⁎ a Department of Food Technology, Naci Topcuoglu Vocational High School, Gaziantep University, 27600, Gaziantep, Turkey b Department of Food Engineering, Faculty of Engineering and Natural Sciences, University of Science and Technology of Adana, 01110, Adana, Turkey c Department of Food Engineering, Faculty of Engineering and Architecture, Nevsehir University, 50300, Nevsehir, Turkey d Olive Research Institute, 35040 Bornova, Izmir, Turkey e Department of Food Engineering, Faculty of Agriculture, Cukurova University, 01330, Adana, Turkey abstract article info Article history: Received 27 February 2013 Received in revised form 28 August 2013 Accepted 12 September 2013 Keywords: Representativeness Olfactometry Aroma compounds Aroma-active compounds Olive oil Aroma and aroma-active compounds of olive oils were analyzed by gas chromatography–mass spectrometry– olfactometry (GC–MS–O). According to sensory analysis, the aromatic extract obtained by simultaneous distilla- tion and extraction (SDE) was representative of olive oil odor. A total of 75, 57, and 71 aroma compounds were identified and quantified in olive oils obtained from Ayvalik, Gemlik and Memecik cvs., respectively. Aldehydes and alcohols were qualitatively and quantitatively the most dominant volatiles in oil samples. Aroma extract di- lution analysis (AEDA) was used for the determination of aroma-active compounds of olive oils. A total of 28, 24 and 32 aroma-active compounds were detected in aromatic extracts of olive oils obtained from Ayvalik, Gemlik and Memecik cvs., respectively. Based on the flavor dilution (FD) factor, the most powerful aroma active com- pounds identified in the extracts were guaiacol (olive paste, soapy) for Ayvalik (FD: 1024), 1-penten-3-ol (grassy, green plants) for Gemlik (FD: 512) and hexanal (cut grass), octanal (citrus, lemon) and (Z)-3-hexenyl acetate (fruity) for Memecik (FD: 1024). © 2013 Elsevier Ltd. All rights reserved. 1. Introduction Growing olives (Olea europaea L.) is a widespread activity throughout the Mediterranean region and is an important issue for the economic activity of the producing areas. According to data re- leased in 2011, Spain comes first with 6,940,230 tons, followed by Italy (3,182,200 tons), Greece (2,000,000 tons), Turkey (1,750,000 tons) and Morocco (1,364,690 tons). Turkey is one of the most important virgin olive oil producing countries in the world, coming after Spain, Italy, Greece and Syria. The olive oil production of Turkey amounted to 177,900 tons in 2011 (FAO, 2012). Olive oil, one of the oldest known vegetable oil, is extracted from the fruits of the olive tree. It has this peculiar property unlike all vegetable oils, in that it can be consumed in the crude form without any further treatments (Kiritsakis, Kanavouras, & Kiritsakis, 2002). It is elaborated from fresh fruits by using easy physical procedures such as milling, malaxing and centrifugation. When olive fruits are harvested at their op- timum maturity stage and are properly processed, olive oil with delicate and unique flavor is obtained. Each olive oil has its own original charac- teristic aroma properties. This property of olive oil is due to its intrinsic aroma compounds of low concentration within its structure (Kiritsakis, 1998; Ranalli, Contento, Schiavone, & Simone, 2001). In addition to cultivar, the degree of fruit ripening, the environment, the growing sea- son, the cultivar practices, the extraction process, in particular the milling and malaxing conditions and the storage conditions affect the aroma pro- files of olive oils (Gomez-Rico, Salvador, La Greca, & Fregapane, 2006). Aroma substances are one of the most significant factors which shape the quality and affect consumer behaviors. Composed of many sub- stances, aroma is the most important factor that defines the sensory at- tributes of olive oil. More than 180 different aromas have been found in olive oil and the majority of these compounds consist of aldehydes, es- ters, hydrocarbons, ketones, and furans (Kalua et al., 2007; Kiritsakis, 1998). Enzymatic reactions and auto-oxidation play crucial roles in the creation of aroma substances. The formation of these compounds starts at the moment of cell disruption during the crushing of the olives and continues during the extraction process (Angerosa, 2002). Only a small fraction of this large number of volatiles in olive oil actually contributes to the overall aroma. With the aid of an “olfactometric technique”, aroma-active substances can be detected in the complex mixture of hun- dreds of aroma compounds. The technology of gas chromatography– olfactometry (GC–O) made it possible to divide identified volatiles into odor-active and non-odor-active compounds with regard to their existing concentration in the studied sample (Garcia-Gonzalez, Tena, & Aparicio, 2007). Limited numbers of researchers have studied the odor- active compounds of olive oils: Reiners and Grosch (1998) studied the potent odorants of virgin olive oils from Italy, Spain and Morocco by aroma extract dilution analyses (AEDA) and GC–O of headspace samples. Food Research International 54 (2013) 1987–1994 ⁎ Corresponding author. Tel.: +90 322 3386173; fax: +90 322 338 66 14. E-mail address: sselli@cu.edu.tr (S. Selli). 0963-9969/$ – see front matter © 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.foodres.2013.09.005 Contents lists available at ScienceDirect Food Research International journal homepage: www.elsevier.com/locate/foodres