2.2.4. GC–MS Analysis

Aroma analysis was carried out in a 6890 N GC coupled to a 5973 N mass spectrometer (Agilent). The stationary phase was a DB-WAX polar capillary column with dimensions of 30 m × 0.25 mm and film thickness of 0.50 μm (Agilent, J&W Scientific, Folsom, CA, USA), while the mobile phase was helium gas at a flow rate of 1 mL/min. The oven temperature conditions were the same as those previously described [18,30]. The oven started at 40 °C, then it raised to 130 °C at 4 °C/min, and finally it rose to 240 °C at 8 °C/min and kept for 5 min.

The temperatures of the MS system were configured in the following way: 270 °C for the transfer line, 150 °C for the quadrupole, and 230 °C for the ion source. The electron impact was fixed at 70 eV and the ionization current was fixed at 10 μA. Both selected ion mass monitoring (SIM) and full scan mode (mass range of 35–350 m/z) were used for data acquisition. The detected peaks were identified by comparing the mass spectra and the retention times with those of the same reference compounds analyzed with the same chromatographic conditions and by using the NIST 2.0 database.

As a result, the absolute peak areas (APAs) of the volatile compounds released in the mouth were obtained. APAs (3 repetitions) were used to compare the 3 in-mouth sampling points.