## 2 Materials and Methods
### 2 Dimensional Gas Chromatography-Time of Flight-Mass Spectrometry  
To aid in the identification of aroma-active compounds and determine volatile profiles for wild lowbush and cultivated highbush blueberry fruit, samples were subjected to GC\(\times\)GC-TOF-MS. Headspace volatile samples were collected from homogenized fruit samples that were prepared as described above. Blanks were made by transferring 10 g of the saturated salt solution into a headspace vial. In addition, retention index standards were prepared by injecting 5 mL of 10 \(\upmu\)L-1 C\({}_{8}\)-C\({}_{20}\) alkanes into a 20 mL headspace vial. All prepared vials were immediately placed in the autosampler rack of a MultiPurpose Sampler (MPS) (Gerstel, Linthicum, MD, USA) for analysis on a Pegasus 4D GC\(\times\)GC-TOF-MS (LECO, St. Joseph, MI, USA). Sample vials were then held at 30 \({}^{\circ}\)C for 5 min, after which a DVB/CAR/PDMS SPME fiber (Sigma-Aldrich Canada Co., Oakville, ON, Canada) was introduced into the vial headspace and allowed to adsorb headspace volatiles for 30 min. The SPME fiber was then desorbed for 3 min at 250 \({}^{\circ}\)C in the injection port of the GC, followed by 4 min of conditioning at 250 \({}^{\circ}\)C. Helium was used as the carrier gas, and the injector operated with a 1:10 split for 1 min following the introduction of the SPME fiber. This split ratio was chosen to maximize detection sensitivity while preventing saturation of the detector. The column flow was maintained at 1.4 mL min\({}^{-1}\). The GC\(\times\)GC system had a polar StabilWAX column (30 m \(\times\) 0.25 mm i.d.\(\times\)0.25 \(\upmu\)m film thickness, Restek Corporation, Bellefonte, PA, USA) for the first dimension and a mid-polar KXI-5 Sil column (0.6 m \(\times\) 0.25 mm i.d. \(\times\)0.25 \(\upmu\)m film thickness, Restek Corporation, Bellefonte, PA, USA) for the second dimension. The two columns were interfaced with a liquid-nitrogen-cooled dual-stage cryogenic modulator and the second column was located in an oven with the temperature program independent of the first-dimension column oven. The GC\(\times\)GC operating conditions were optimized using Simply GC\(\times\)GC TM (LECO, St. Joseph, MI, USA). The temperature program for the primary GC oven was set at 50 \({}^{\circ}\)C for 0.2 min, then ramped at 10.3 \({}^{\circ}\)C min\({}^{-1}\) to 220 \({}^{\circ}\)C. The secondary oven was maintained 33 \({}^{\circ}\)C warmer than the primary oven. The modulation period, the hot-pulse duration and the cooling time between stages were set at 1.3, 0.39 and 0.26 s, respectively. The transfer line to the TOF-MS detector source was maintained at 250 \({}^{\circ}\)C. The ion source temperature was 250 \({}^{\circ}\)C with a filament voltage of 70 eV. The data acquisition rate was 200 spectra s\({}^{-1}\) for the mass range of 35-300 amu. Mass calibration and tuning were conducted daily using perfluorotributylamine (PFTBA).  
Compound identification was based on the retention index (RI) and similarity with the National Institute of Standards and Technology (NIST) Mass Spectral Virtual Library (ChemSW, Fairfield, CA, USA). Identifications were also confirmed using known standards when available. Data were processed using LECO ChromaTOF software (LECO, St. Joseph, MI, USA), and an estimate of the peak area counts of each compound was calculated using the LECO APEX data deconvolution/processing routine.  
To aid in the identification of aroma-active compounds that were present in low concentrations, additional analyses were conducted. To increase the sensitivity of detection, 20 g of fruit tissue was homogenized in 30 g of a saturated NaCl solution and 10 mL of this homogenate was transferred to a 20 mL headspace vial. Analysis of the headspace volatiles was conducted as described above, except the injector operated with a 1:5 split for 1 min following the introduction of the SPME fiber to the GC injection port.