## 2 Materials and Methods
### Identification of Volatile Organic Compound and Data Calculations  
The peaks were identified by a mass spectrometer (5973 Network Mass Selective Detector, Agilent Technologies) coupled to the GC, comparing the experimental spectra with those of NIST 11 MS library (National Institute of Standards and Technology, Gaithersburg, MD, USA). The chromatographic analysis data for the volatile compounds were automatically integrated using MSD ChemStation software (F01 001 1903 2013, Agilent Technologies). To reduce the number of additional peaks that would need to be manually introduced in the subsequent deconvolution process, the automatic Chemstation parameters were set as follows: initial area reject 0; initial peak width 0.045; shoulder detection off; initial threshold 14.0. These preliminary data only served as a basis for manual integration, deconvolution, and individual reverification of the peaks based on deconvolution analysis using NIST 11 MS library and the automated mass spectral deconvolution and identification system AMDIS (version 2.7, 2011, National Institute of Standards and Technology, Gaithersburg, MD, USA). Data for the best deconvolution models were selected from those offered by automatic mass spectral deconvolution and identification system (AMDIS) according to the higher match quality index for the target compound (usually 2-3 models, and always less than five models per peak). After several trials with different options, the deconvolution settings of AMDIS were: component width equal to 16, two adjacent peak subtractions, low resolution, very high sensitivity, and low shape requirements. These parameters can be modified, especially to obtain the results for some flat peaks (i.e., some alkanes or poorly detectable compounds) that cannot always be confirmed with the above parameters: for example, by increasing the resolution to high. Chemical compounds were verified by a comparison of linear retention indices (LRI) calculated with a homologous series of n-alkanes (C6-C20; Sigma-Aldrich) for the HP-5 MS UI column [18] and analyzed under the same conditions. Propane, butane, and pentane retention times were estimated based on previous analysis of several seasons. LRI were compared with the literature results compiled by NIST [19], although sometimes the LRI data were estimated from the non-polar retention index (\(n\)-alkane scale) offered by NIST MS Search 2.0. We also used a profile of melon VOC LRIs (more than 500 compounds) obtained in hundreds of previous analyses using cultivars of different types and the same methodology, and others with HP-5 MS columns [20] ([PERSON] et al., 2013). A coefficient of variation for \(LRI\) was calculated as follows:  
\[\mathrm{CV_{LRI}}\ =\ \frac{(LRI\ \mathrm{calculated}\ -\ LRI\ \mathrm{literature})}{LRI\ \mathrm{literature}}\ \times\ 100 \tag{1}\]  
The compounds accepted always showed \(\mathrm{CV_{LRI}}\)! % (usually less than 0.5%). The concentration of the individual aroma volatile compounds identified (expressed as ng\(\cdot\)mL\({}^{-1}\) of juice) was quantified from the relation between their areas and that of the internal standard (1-phenylethanol), obtained from the total chromatograms, using a response factor of 1 [6]. The IUPAC names of individual aroma volatiles were verified with the CAS number of the NIST database [19] in accordance with several databases [21; 22]. The chemical volatile compounds were classified into eleven groups, according to [PERSON] et al. (2013) [5]: volatile acids (ACD); acetate esters (ACE); alcohols (ALC); aldehydes (ALD); alkanes (AHA); ketones (KET); non-acetate esters (NAE); sulfur-derived compounds (SDC); terpenes (TER); others (OTH). Unidentified (NID) compounds which did not demonstrate a clear comparison with the NIST11 database were not included in the main analysis. Each fruit was classified by the number of replicates (21 in season 1, and nine in season 2) and a letter (A, B, C or D), and sometimes by adding the letter \"r\", indicating re-analysis of the same individual fruit sample.