## Materials and Methods
### Analysis of Free and Bound Volatile Aroma Compounds  
Headspace Solid-Phase Microextraction--Gas Chromatography/Mass Spectrometry (HS SPME--GC/MS Analysis)  
Free fraction. A volume of 10 mL of juice, 10 mL of 4-methyl-2-pentanol (internal standard, 1 mg/L standard solution in methanol, Merck, Darmstadt, Germany), and 3 g NaCl (p.a.) were added into a 20-mL vial. The vial was sealed with an aluminum cover and Teflon-lined cap, and the sample was pre-conditioned in a temperature-controlled heating module at 45 \({}^{\circ}\)C for 30 min and agitated at 350 rpm. Volatile aroma compounds were isolated using headspace solid-phase microextraction (HS-SPME) according to the modified method of [PERSON] et al. [22] and analyzed by gas chromatography/mass spectrometry. SPME fibers coated with CarboxenTM/polydimethylsiloxane (1 cm long, 85 \(\upmu\)m thick) were purchased from Supelco (Bellefonte, PA, USA). For desorption, the fiber was inserted into a GC/MS injector port at 270 \({}^{\circ}\)C in the splitless mode for 2 min.  
Identification and quantification of volatile compounds was performed using a gas chromatograph (Agilent 7890 Series GC system) coupled to a 5975C mass selective detector (Agilent, Santa Clara, CA, USA) equipped with a MPS2 Multipurpose autosampler (Gerstel, Baltimore, USA). A DB-5 capillary column was used (60 m \(\times\) 0.32 mm i.d., with 1 \(\upmu\)m film thickness) (Restek, Bellefonte, PA, USA). The initial oven temperature was held at 40 \({}^{\circ}\)C for 2 min, then raised at 5 \({}^{\circ}\)C/min up to 150 \({}^{\circ}\)C, held at 150 \({}^{\circ}\)C for 5 min, raised to 250 \({}^{\circ}\)C at 5 \({}^{\circ}\)C/min, and held at 250 \({}^{\circ}\)C for 5 min. Helium was the carrier gas with a flow rate of 1.3 mL/min at 40 \({}^{\circ}\)C. The detector operated in the m/z range between 30 and 250. The ion source and quadrupole temperature were maintained at 250 and 150 \({}^{\circ}\)C, respectively. Identification of compounds was performed by comparing retention times and mass spectra with those of available commercial standards and with mass spectra from the NIST mass spectral database (National Institute of Standards and Technology, USA). When standards were not available, compounds were tentatively identified by comparing their mass spectra with those in the NIST library. Tentative identification was considered successful for compounds with the MS spectra match probability higher than 80.0%. Standard calibration curves were constructed for quantification of compounds. Results were expressed as the concentration of compounds calculated from the peak area of the individual compounds in comparison to the peak area of internal standard. The repeatability of the experimental method was determined by performing three replicate analyses of each juice sample. Calculated relative standard deviations (RSD %) of peak areas were less than 10%.  
Bound fraction. All compounds in the juice were extracted by mixing with 2 M citric acid and subjected to acidic hydrolysis (pH 2.5) according to the modified method described by [PERSON] et al. [23]. After adding internal standard, 10 mL of hydrolyzed extract were stirred by the CarboxenTM/polydimethylsiloxane (1 cm long, 85 \(\upmu\)m thick)-coated fiber at 45 \({}^{\circ}\)C for 30 min.  
Both free and bound compounds extracted onto the fiber in this procedure, and the bound fraction of each compound was obtained by subtracting its corresponding free concentration.