Abstract: Volatile compounds of fresh blood orange juice were analyzed by solid phase microextraction and gas chromatography-mass spectrometry (SPME-GC-MS) and the aroma active compounds were identified by olfactometry. The volatile compounds were extracted by headspace solid phase microextraction (HS-SPME) using a divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS) fiber for 40 min at 40 ℃. The analysis was carried out using an HP 6890N GC equipped with an HP-5 column (30 m×0.25 mm×0.25 μm ) directly connected to an HP 5975 series mass selective detector and a sniffing port (ODP2, Gerstel) using helium as carrier gas. Compound identifications were made by the comparison of the mass spectra, retention times, retention indices (IR) and odor of the volatile components in the extracts with those of the corresponding reference standards. Forty-six compounds were identified by GC-MS and IR. The major components of the juice were limonene (86.36%), linalool (3.69%), β-myrcene (1.79%), octanal (1.32%) and valencene (1.27%). GC-MS-olfactometry analysis was performed to determine 34 compounds with aroma activity, of which 23 compounds were identified. The major contributors to orange juice aroma activity are ethyl butanoate, octanal, γ-terpinene, 4-acetyl-1-methylcyclohexene, decanal, (-)-carvone, geranyl acetate, valencene. These compounds of strong aroma intensity represent 7.22% of the total volatile compounds. Other four unknown compounds (IR<800; IR=1020, 1143, 1169, separately) are also the major contributors to the overall aroma.

Key words: aroma active compounds, blood orange , gas chromatography-mass spectrometry (GC-MS), olfactometry, retention index, solid phase microextraction (SPME)