## 3 Results
### Brewing Trials: Evaluation of Growing Area on Hop Quality Traits  
Figure 4 shows the FTIR molecular fingerprinting of different hop samples used in the brewing trials (2018 vintage), acquired in the MIR region. As can be seen, the IR signature highlighted significant differences among samples, mainly in the spectral regions 3000-2800 cm\({}^{-1}\), 1800-1400 cm\({}^{-1}\) and <1100 cm\({}^{-1}\). The first broad band located at about 3270 cm\({}^{-1}\) was attributed to the O-H stretching, which was associated with the presence of water in the matrix and/or carboxyl groups present in compounds such as polyphenol acids, also reported in hop cones [13; 23]. Two sharp peaks centered at 2916 and 2849 cm\({}^{-1}\), related to the symmetric and asymmetric stretching of methylene groups, characteristics of lipids and fatty acids as well as of aromatics [24], were also visible in this region and they were more pronounced in the CAS_T samples (Figure 2b). Interestingly, the CAS_T samples were also characterized by a small but clear band (2954 cm\({}^{-1}\)) to the left of the intense signals due to the aliphatic stretching, which could be attributed to the stretching of =C-H of terminal group in non-conjugated alkenes as well as to the stretching of aromatic ring C-H bonds. The fingerprinting region between 1800 and 700 cm\({}^{-1}\) showed significant differences between the two samples analyzed. The spectral band centered at 1735 cm\({}^{-1}\) was attributed to the stretching of the C=O bonds in saturated esters and \(\delta\)-lactones. Superimposing the graphs of the second-derivative IR spectra (Figure 4a,b; red lines) on the raw IR spectra in the range from about 1700 cm\({}^{-1}\) to about 1400 cm\({}^{-1}\), allowed the analysis of the overlapping peaks, such as amide I band components in the spectral region of 1690-1630 cm\({}^{-1}\) and the bending absorption of NH bond (amide II) in the region 1570-1510 cm\({}^{-1}\). As can be seen from Figure 4, these bands were present in the sample  
Figure 3: (**a**) PCA score plot of hop samples from different locations based on FTIR data matrix; (**b**) Loading plot of the spectral variables most contributing to the separation of hop samples on PC1 and PC2. from Latium and absent in the sample coming from Tuscany, which showed far fewer absorption bands in this spectral range than the other sample analyzed (Figure 4b). From derivative spectrum of CAS_L sample (Figure 4a, red line), two bands at about 1580 cm\({}^{-1}\) and around 1500 cm\({}^{-1}\) were observed, highlighting the presence of conjugated aromatic rings. Besides, another two bands in the derivative spectrum of CAS_L sample (Figure 4b) centered at 1652 cm\({}^{-1}\) and 1578 cm\({}^{-1}\) were observed, which could be attributed to the absorption of the ring carbonyl bond and to the keto-enol carbonyl stretching vibrations of lupolones, respectively [25]. Both hop samples showed two sharp bands centered at about 1470 and 1460 cm\({}^{-1}\) due to the stretching of the double aromatic bond. Table 1 shows the main chemical quality parameters of hop samples used in the brewing trials. Both total \(\alpha\)- and \(\beta\)-acid content of the two hop samples analyzed were in line with the reported values for the Cascade variety (4.5-8.9% for \(\alpha\)-acids; 3.6-7.5% for \(\beta\)-acids) [6; 9]. The hop cones from Tuscany showed significant higher values of bitter acids compared to CAS_L ones (\(p<0.05\)), highlighting a growing area effect on hop bitter acid content as also reported in the literature [6]. Interestingly, both hop samples showed a very low cohumulone content, in contrast to that reported by technical data sheets for Cascade variety and by international studies, in which it was always above 21% (on average 33-40%; [6; 9]. Low levels of cohumulone are often associated with great beer foam stability and the so-called noble hops are characterized by a cohumulone ratio of 25% or less [26]. In the present study, both hop samples showed comparable and good values of HSI [8].