Characterization of aroma compounds in Portuguese extra virgin olive oils from Galega Vulgar and Cobrancosa cultivars using GC-O and GC x GC-ToFMS

Aroma compounds of virgin olive oils extracted from two olive cultivars - Galega Vulgar and Cobrancosa - grown in Beira Baixa region in central Portugal were investigated. Gas chromatography-olfactometry (GC-O) was carried out to select the important odorants for subsequent comprehensive gas chromatography/time of flight mass spectrometry (GC x GC-ToFMS) analysis. By GC-O fifteen odorants were identified. For the quantification of volatile compounds, headspace solid phase microextraction (SPME) technique was optimized. Under optimized conditions, 22 volatile compounds were quantified in all samples. Trans-2-hexenal was the most abundant compound. A discriminant analysis (DA) was used to discriminate among olive oil samples obtained from olives of the two cultivars with different harvest time/ripening stages. Concerning the harvesting time and cultivar, nine volatiles showed to have discriminant power among samples, namely heptanal, trans-2-hexenal, 1-octen-1-ol, nonanal, 2,3-butanedione, ethyl-2-methylbutyrate, henna], cis-3-hexenylacetate and 3-methylbuthylacetate. (C) 2013 Elsevier Ltd. All rights reserved.