GC–O analysis was performed on a GC equipped with MS and a sniffing port (ODO II; SGE, Melbourne, Australia). Analytical conditions were the same as those for GC–MS analysis. A TR-5ms column (30 m × 0.25 mm × 0.25 μm, J&W Scientific,) was used for GC–O. The end of the capillary column was connected to the splitter, which divides the effluent into two equal parts. The carrier gas was transferred to the MS and a sniffing port, respectively, via two deactivated fused silica capillaries (50 cm × 0.25 mm). Auxiliary gas helium ran at 3.0 on the flow-meter scale. During a GC–O run, the transfer-line tubing was heated and the sniffing cone was purged with humidified air to reduce olfactory fatigue by dehydration of human nasal mucous membranes and maintain olfactory sensitivity. Each aroma-active compound detected has an FD factor, representing the highest split ratio at which the odorant could be perceived at the sniffing port. Olfactometry analysis was carried out by three trained panellists and repeated twice by each assessor. Then, the FD factor was defined as the dilution step at which a compound was detected at least half of the six times.