## 3 Results and Discussion
### Spectral Analysis  
Figure 1A shows the characteristic FTIR spectra of the fresh pulps. Overall, the spectra are similar regarding the position of the characteristic peaks. However, the intensity of various peaks, particularly those between 1200 and 500 cm\({}^{-1}\), varies notably, which supports the feasibility of obtaining quantitative information on the chemical composition of _Cucurbita_ species from these spectra. In the spectra of fresh pulps, the \(\beta\)-carotene and lutein bands could be overlapped with the peaks of the functional groups of other molecules. However, it is possible to distinguish some characteristic peaks of these compounds, such as 960.1 cm\({}^{-1}\) and 963.1 cm\({}^{-1}\), as observed in the spectra of the pure compounds (Figure 2). The peak around 1550-1600 cm\({}^{-1}\) corresponds to C=C double bond stretching vibrations of \(\beta\)-carotene [20]. The region of approximately 1450 cm\({}^{-1}\) is associated with vibrations of antisymmetric deformation of CH\({}_{3}\) groups (change in HCH angles) and CH\({}_{2}\) groups (scissor vibrations) [20,21]. Likewise, the bands located around 1360-1390 cm\({}^{-1}\) are likely the result of the \"umbrella\" vibrations of the CH\({}_{3}\) groups [21]. The most intense peak of the spectra, located in the range 950-980 cm\({}^{-1}\), corresponds to the deformation vibrations of the C-H bonds in the polyene chain, whereas the band located at approximately 520-530 cm\({}^{-1}\) is associated with the change in the angles and deformation of the polyene chain [21,22]. In these spectra, it is also possible to identify a characteristic band around 1100 cm\({}^{-1}\); this absorbance peak corresponds to the C-O stretch vibrations of alcohols, which probably arises from xanthophylls, such as lutein. Indeed, this band is recognizable in the FTIR spectra of the pure compound (Figure 2). However, it might be also associated with the presence of other compounds with alcohol functional groups in the pulp of spp. _Cucurbita_[23, 24, 25]. There is a remarkable similarity of the spectra of Figure 1A with those reported for pectin-rich pumpkin extracts [26]. The same broad intense peak located between 3000 to 3600 cm\({}^{-1}\) was observed, which is associated with the oscillations of the -OH groups of water. Furthermore, the bands of 2926 cm\({}^{-1}\) (functional groups with C-H bonds), the spectral region 1500-2000 cm\({}^{-1}\) (oscillations of C=O  
Figure 1: Characteristic FTIR-ATR spectra of the samples of _Cucurbita_ sp. (\(n=63\)) with different sample processing protocols: (**A**) fresh pulp (blender-homogenized); (**B**) freeze-dried pulp; (**C**) hexane:acetone (1:1) extracts. Figure 2: FTIR-ATR spectra of pure \(\beta\)-carotene and lutein. bonds), and regions such as 1730-1760 cm\({}^{-1}\) (corresponding to COO-R bonds) and 1600-1630 cm\({}^{-1}\) (corresponding to COO- bonds), were identified in pumpkin pectin-rich extracts [26]. All the above indicates that, besides carotenoid compounds, the characteristic FITR spectra of _Cucurbita_ spp. pulp, shown in Figure 1A, are determined also by the presence of pectin, and possibly other polysaccharides. In the freeze-dried pulp spectra, shown in Figure 1B, the relative absorbance of the broad and intense peak, with a maximum between 3200 and 3600 cm\({}^{-1}\), which corresponds to oscillations of the -OH groups of the water molecule, is reduced due to the freeze-drying process. In these spectra, it is possible to appreciate the same characteristic bands of the spectra of the fresh pulps: 2926 cm\({}^{-1}\) that corresponds to the oscillation of groups with C-H bonds, 1550 cm\({}^{-1}\), associated with double bonds of \(\beta\)-carotene. One of the typical bands of \(\beta\)-carotene and lutein can also be observed around 968 cm\({}^{-1}\)[27]. Figure 1C shows the spectra of the extracts in hexane/acetone. As in the spectra of the pure compounds (Figure 2), it is possible to identify in the extracts the characteristic band of \(\beta\)-carotene at 3000 cm\({}^{-1}\).