## 2 Materials and Methods
### Ester Analysis
#### 2.4.4 Headspace Solid-Phase Microextraction Gas Chromatography Mass Spectrometry (HS-SPME-GC-MS)  
Stableflex Divinylbenzene/Carboxen/Polydimethylsiloxane (DVB/CAR/PDMS) SPME fibers (50/30 \(\upmu\)m thickness, 2 cm long, 24 gauge) were purchased from Supelco (Bellafonte, Pennsylvania, USA). This fiber is compatible with the analysis of volatile and semi-volatile flavor compounds containing 3-20 carbon units. Extraction and desorption conditions were optimized to obtain the best compromise for the simultaneous analysis of all 30 studied esters. To provide specificity for the method, deuterated ethyl esters were used as internal standards. The SPME fiber was conditioned at 250 \({}^{\circ}\)C in the injection port for 1 h prior to use on a conditioning station attached to the Combi-Pal autosampler used with the Shimadzu GC-MS instrument (Shimadzu Scientific Instruments, Kyoto, Japan). The SPME fiber was further conditioned before each sample analysis at 250 \({}^{\circ}\)C for 10 min and replaced with a new one after approximately 224 samples.  
Calibration curves of all ester compounds were calculated using two methods. It was not possible to employ a single GC-MS procedure to determine all compounds measured in this study due to a few compounds having similar retention times, which required two headspace-solid phase microextraction (HS-SPME)-GC-MS methods to achieve the desired separation and the sensitivity needed for accurate quantitation.  
**Method 1**: Nineteen ester compounds were analyzed by adapting a method for the quantitative determination of wine esters by (HS-SPME)-GC-MS [29]. Briefly, samples were analyzed in a Shimadzu QP2010 GC-MS instrument (Shimadzu Scientific Instruments, Kyoto, Japan) equipped with a CTC Combi-Pal autosampler (CTC-Analytics) and with a split injector. The chromatography configuration contained two columns connected in sequence, Stablewax (30 m \(\times\) 0.25 mm ID \(\times\) 0.25 \(\upmu\)m film thickness, Restek Corp., Bellefonte, PA, USA) connected to an Rxi column (15 m \(\times\) 0.25 mm ID \(\times\) 0.25 \(\upmu\)m film thickness, Restek Corp., Bellefonte, PA, USA) using a universal press-tight connector (Restek Corp., Bellefonte, PA, USA). The method parameters for the oven were as follows: the injector temperature was set at 250 \({}^{\circ}\)C. The column oven was held at 35 \({}^{\circ}\)C for 10 min and then increased to 250 \({}^{\circ}\)C at 4 \({}^{\circ}\)C/min and held at this temperature for 10 min. The flow control mode was set using the pressure mode at a constant 32.2 kPa. The prepared diluted (tenfold) samples were incubated and agitated for 10 min at 60 \({}^{\circ}\)C. The GC used helium as the carrier gas, set at a linear velocity of 21.5 cm/s. The ion source and interface temperatures were set at 200 \({}^{\circ}\)C and 250 \({}^{\circ}\)C, respectively. The MS spectra were operated in electron impact (EI) mode at an ionization energy of 70 eV, switching between full scan mode and selective ion mode (SIM), with variable gain factors for SIM mode (Tables S3 and S4). The total run time was 73.75 min per sample. The MS acquisition mode was set to full scan for all 41 compounds. The NIST05 (National Institute of Standards and Technology) mass spectral library and reference standards, composed of pure compounds, were used to confirm the identities of all standards used. Quantitative parameters for all compounds and labelled standards are shown in Table S1.  
**Method 2**. Nineteen ester compounds were analyzed using a similar procedure to method 1. Quantitative parameters for all compounds and labelled standards are shown in Table S2. The oven ramp and MS spectra mode for full scan and SIM modes were altered from method 1 based on the different compounds analyzed (Tables S5 and S6). The column oven was held at 35 \({}^{\circ}\)C for 10 min, and then increased to 200 \({}^{\circ}\)C at 4 \({}^{\circ}\)C/min and held at this temperature for 1 min, then increased to 250 \({}^{\circ}\)C at a rate of 10 \({}^{\circ}\)C/min and held at that temperature for 5 min.