Characterization of aroma compounds in Portuguese extra virgin olive oils from Galega Vulgar and Cobrançosa cultivars using GC–O and GC×GC–ToFMS

Aroma compounds of virgin olive oils extracted from two olive cultivars – Galega Vulgar and Cobrançosa – 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×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, hexanal, cis-3-hexenylacetate and 3-methylbuthylacetate. •Gas-chromatography–olfactometry was performed for Galega and Cobrançosa olive oils.•Headspace solid phase microextraction technique was optimized.•22 compounds were quantified by GC×GC–ToF-MS.•The major component contributing for olive oils aroma was trans-2-hexenal.•9 volatiles discriminate among sample cultivars at different harvesting times.