## 3 Results and Discussion
### Quali-Quantitative Composition  
Looking at Figures 1 and 2, the \({}^{1}\)H NMR profile of the PWS sample appears much more complex. Consequently, the complete assignment of the obtained spectrum was not simple and involved 2D and selective experiments (1D-DPFGSE-TOCSY) to support the overall data consistency including the detected spin systems. Such a complexity is essentially related to the intrinsic sample heterogeneity, so that different chemical families were detected, such as aminoacids, sugars, nucleosides, organic acids and alcohols. Provided that these data are generally matching previous findings [22; 23; 24] and are consistent with general libraries [36; 37], the tedious updated assignment (Table S1, Electronic Supplementary Materials) is updated according to slight mismatches like the fine septuplet structure of the \(\alpha\)-CH of MHP (methyl hydroxy proline) and the detected presence of the 1,2-propanediol (PDO). This basic knowledge was necessary in order to enable the robust MARA-NMR algorithm which processed 63 \({}^{1}\)H-NMR integrations leading to the quantification of 39 PWS substances (Table 1).  
Specifically, sugars were the most abundant compounds of PWS, indeed sucrose is the main component and farinose is often very well represented. \(N\)-methyl-4-trans-hydroxyproline was the most concentrated amino acid derivative, followed by glutamate or arginine depending on the specific sample. Some organic acids (citrate and malate) and other less represented amino acids (proline, alanine and \(\gamma\)-aminobutyrate) were also interesting variables for the pistachio characterization. Afterward, the same MARA-NMR approach was adopted for the PO fractions according to the architecture previously built and already investigated for olive oil samples [21; 34] able to combine both \({}^{1}\)H and \({}^{13}\)C profiles. The main hydrophobic components were fatty acid esters, consisting of triacylglycerlycerols (>90% of the total glyceridic fraction), and diacylglycerols (between 2.1% and 5.7% of the total glyceridic fraction). Oleic esters (O%) represent more than 50% of fatty esters, followed by linoleic acid (L%) with a relative content between 13.5% and 28.4%; this is pretty fitting literature data [22]. A small amount of  
Figure 2: Main spectral region for the \({}^{1}\)H-NMR profile at 500 MHz of the CDCl\({}_{3}\) soluble fraction (PO) extracted from pistachio powder (sample from Bronte). Arrows display the main assignment connections, according to the symbol codes in Table 1, subsequently processed by MARA-NMR algorithm (see Table S3 for technical details).  
\"methylated sterols\" was also observed and used for the statistical analysis, since it was considered a potential discriminant feature for the geographical differentiation [28]. Hence, the method has led to the evaluation of six independent chemical parameters out of eight total quantification parameters due to mathematical restrains: the sum of fatty acid esters is set to 100% as well as the sum of di-acyl glycerols and tri-acyl glycerols. The comprehensive analysis of PWS and PO has eventually provided 47 quantitative chemical parameters extensively reported in Table S2. All the identified compounds play a very important role in many metabolic pathways, thus confirming the suitability of the NMR technique for metabolomic studies.