## Materials and Methods
### GC-MS-Olfactometry System  
The analysis was performed on a standard 6890N GC/5973 Network Platform (Agilent Technologies, Santa Clara, CA, USA) and a CTC CombiPal(tm) autosampler equipped with a heated agitator (Trajan Scientific, Pflugerville, TX, USA). A constant agitation speed of 500 rpm was used throughout this research, so that extraction would only depend on the SPME fiber geometry and diffusion coefficients of the aroma compounds. The instrument was modified after marketing with a Dean's switch for heartcutting, the ability for cryogenic focusing, FID, and the olfactometry port. A detailed schematic of the instrument can be found elsewhere [15]. The GC contains two columns connected in series. The first non-polar column was BPX-5 stationary phase with the following dimensions: 43.5 m length \(\times\) 0.53 mm ID \(\times\) 1.0 \(\upmu\)m film thickness (SGE Analytical Science, by Trajan, Austin, TX, USA). The second cross-linked polar column was BP-20 (Wax) with the following dimensions: 25 m length \(\times\) 0.53 mm ID \(\times\) 1.0 \(\upmu\)m film thickness (SGE Analytical Science, by Trajan, Austin, TX, USA). A constant pressure of 5.8 psi was provided at the midpoint between the first and second column using MultiTrax(tm) V.6.00 (Microanalytics, a Volatile Analysis company, Round Rock, TX, USA) system automation and MSD ChemStation(tm) E.01.01.335 data acquisition software (Agilent Technologies, Santa Clara, CA, USA). Additional analysis to obtain the total compound chromatogram (TCC) was done using a MassHunter Workstation (Agilent, Santa Clara, CA, USA). Flow from the second analytical column was directed to the single quadrupole mass selective detector and the olfactometry port by fixed restrictor tubing in an open-split interface.  
For this research, a full heartcut was utilized from 0.05 to 35.00 min. In other words, the sample flow was first directed through the non-polar column, and then the second polar column, yielding results similar to a mid-polarity GC separation on a long column. Therefore, retention indices were not used for identification in this research, due to the configuration of the two GC capillary columns connected in series.  
The following instrument parameters were used: GC inlet temperature, 260 \({}^{\circ}\)C; FID, 280 \({}^{\circ}\)C; column, 40 \({}^{\circ}\)C initial, 3.0 min hold, 7 \({}^{\circ}\)C per min ramp, 220 \({}^{\circ}\)C final, 11.29 min hold; carrier gas, UHP helium (99.999%) with an inline filter trap. The mass detector was operated in electron ionization (EI) mode with an ionization energy of 70 eV. The mass detector ion source and quadrupole were held at 230 \({}^{\circ}\)C and 150 \({}^{\circ}\)C, respectively. Full spectrum scans were collected with the mass filter set from \(m/z\) 33 to \(m/z\) 450. The MS was auto-tuned daily before analysis. The use of a full scan for data acquisition allowed for library search techniques using NIST05 and Wiley 6 th edition mass spectral databases.  
Olfactometry data was generated using AromaTrax(tm) V.6.61 software (Microanalytics, a Volatile Analysis company, Grant, AL, USA). Recorded parameters included an aroma descriptor and the perceived intensity. The editable descriptor panel is shown in Figure 1. The area under the peak of each aroma note in the aromagram is calculated as width \(\times\) intensity \(\times\) 100, where the width is the length of time that the aroma persisted in minutes. The sum of the areas under the peaks in the aromagram is the total odor, a dimensionless value used to analyze the total aroma detected by the human nose.  
Figure 1: Aroma descriptor panel used to characterize volatiles and perceived intensities.