## 4 Materials and Methods
### Aroma Precursors
#### 4.3.2 Bound Precursors and Thiol Precursors  
Bound aromas and thiol precursors were determined at Fondazione Edmund Mach (FEM, San Michele all'Adige, Italy). Bound aromas were extracted and quantified by gas chromatography, according to [PERSON] et al. (2018) [112]. The extraction was performed by adsorption on an SPE cartridge (ENV+, 1 g) previously conditioned with 20 mL of methanol and 20 mL of Milli-Q water. The sample was loaded onto the cartridge, which was washed with 20 mL of Milli-Q water and eluted with 30 mL of methanol. This solution was evaporated and then dissolved in 4 mL of citrate buffer at pH 5. 200 \(\upmu\)l of a glycosidic enzyme with strong glycosidase activity (AR 2000 at 70 mg/mL in water) were added, and the solution was kept in a 40 \({}^{\circ}\)C water bath overnight. After the addition of 1-heptanol (0.1 mL) as an internal standard, the free volatiles released were extracted using an SPE cartridge (ENV+, 200 mg) previously conditioned with 10 mL of methanol and 10 mL of Milli-Q water and eluted with 4 mL of dichloromethane. The organic phase was dried. Volatile organic compound analysis was performed using an Agilent Intuvo9000 fast GC system coupled with an Agilent 7000 Series Triple Quadrupole MS equipped with an electron ionization source operating at 70 eV. The filament current was 50 \(\upmu\)A. Separation was obtained by injecting 2 \(\upmu\)L in split mode (1:5) into a 20-m DB-Wax Ultra Inert (0.18 mm ID \(\times\) 0.18 \(\upmu\)m film thickness) with He as carrier gas (at a flow of 0.8 mL/min). The oven temperature was programmed starting at 40 \({}^{\circ}\)C for 2 min, raised to 55 \({}^{\circ}\)C by 10 \({}^{\circ}\)C/min, then raised to 165 \({}^{\circ}\)C by 20 \({}^{\circ}\)C/min, and finally raised to 240 \({}^{\circ}\)C by 40 \({}^{\circ}\)C/min and held at this temperature for 5 min. The mass spectra were acquired in multiple reaction monitoring modes, setting the instrument within the dynamic system. Nitrogen was used as the collision gas, with a flow of 1.5 mL/min. The transfer line and source temperature were set at 250 \({}^{\circ}\)C and 230 \({}^{\circ}\)C, respectively.  
Thiol precursors were estimated using liquid chromatography, according to [PERSON] et al. (2021) [113]. The QuECHERS method was used to extract the sample with an extraction buffer composed of acetonitrile. After incubation at 8 \({}^{\circ}\)C for 2 h, a 1 ml aliquot of the supernatant sample extract was transferred to an autosampler vial (volume 2 mL), and 75 \(\upmu\)L of Ebiselen (ACN solution at 500 mg/L) was added. The vial was then stirred for 10 min. The derivatized sample was filtered (0.22 \(\upmu\)m PTFE) and then transferred into an auto-sampler vial before the injection. A Waters Acquity UPLC (Waters Corporation, Milford, MA), coupled to a Xevo TQ MS mass spectrometer equipped with an electrospray ion source (Waters), was used. The chromatographic module consisted of an Acquity UPLC BEH C18 column (1.7 \(\upmu\)m, 2.1 mm \(\times\)100 mm) working at 40 \({}^{\circ}\)C. 0.1% (\(v/v\)), aqueous formic acid (solvent A), and 0.1% (\(v/v\)) formic acid in MeOH (solvent B) were used at a flow rate of 0.45 mL/min. The gradient conditions of the LC mobile phase were as follows, based on times (t): t = 0-0.25 min, hold 80% A, 20% B; t = 0.25-7 min, ramp linearly to 100% B; t = 7-8.5 min, hold 100% B. The sample (2 \(\upmu\)L) was injected using the partial loop needle overfill' function. The mass spectrometer was used in positive electrospray ionization mode (ESI+), and the source conditions were set as follows: capillary voltage 0.6 kV; source temperature 150 \({}^{\circ}\)C; cone gas flow (nitrogen, 20 L/h); desolvation gas flow (nitrogen, 1000 L/h); desolvation temperature 500 \({}^{\circ}\)C. Argon, used as collision gas, was set at 0.20 mL/min.