## 3 Results
### Characterization of Permeates and Retentates
#### 3.2.2 FTIR
820, 772 cm\({}^{-1}\) and others indicated in Table 2) correspond to the characteristic oscillations of theomeric region of carbohydrates or deformation C-H. Moreover, the relatively intensive bands with maxima at approx. 770 cm\({}^{-1}\) are bands associated with the oscillations of the anomeric region of carbohydrates or deformation C-H (\(\delta\) (C-H)). The region is characterised by considerable differences between particular samples, which evidences a significant change in terms of bond conformation in various sugar fractions (glycoside bond). Significant discrepancies between UF and DF samples were also observed in terms of bands with the maxima at approx. 1412 cm\({}^{-1}\). Oscillations in the aforementioned spectral band are characteristic of O-CH and C-C-H deformation oscillations in the carbohydrate structure, or deformation oscillations originating from the -OH group in the C-OH grouping. According to [PERSON] et al. [45], they may also be related to the presence of organic acids, caroten, and polyphenols. Changes in this region clearly evidence smaller amounts of particular sugar fractions in the samples subjected to the DF process. However, particularly significant discrepancies between all the samples were observed in the area from 1750 to 1550 cm\({}^{-1}\), which corresponds to the oscillations of the carbonyl C=O group of fructose and aldehyde CH=O of glucose [41; 43; 46]. In particular, the decrease in the intensity of those bands was observed in samples subjected to the DF process (PDF and RDF) when compared to both UF samples. One should also emphasise the near complete disappearance in DF samples in the aforementioned area of the band with the maximum at approx. 1580 cm\({}^{-1}\) which, alongside the aforementioned bands, may also correspond to the stretching oscillation of the N-H group in the band of free amino acids. Oscillation with the maximum at approx. 1640 cm\({}^{-1}\) corresponds to the stretching vibration of C-H bonds that constitute the chemical skeleton of sugars. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multicolumn{5}{c}{**Position of Bands (cm\({}^{-1}\))**} & \multicolumn{3}{c}{**Type and Origin of Vibrations**} \\ \hline
**ACJ** & **RUF** & **PUF** & **PDF** & **RDF** \\ \hline
3344 & 3345 & 3339 & 3334 & 3344 & \(\forall\)(–OH) \\ \hline
2917 & 2920 & 2923 & 2916 & 2929 & \(\forall_{\text{as}}\)(–C–H\({}_{\text{m}}\), –CH\({}_{3}\), –CH\({}_{2}\)) \\  & & & & \(\forall_{\text{as}}\)(–C–H\({}_{\text{vst}}\), –CH\({}_{2}\)) \\  & & & & & and \\  & & & & & \(\forall_{\text{s}}\)(–C–H\({}_{\text{vst}}\), –CH\({}_{\text{a}}\)) (aliphatic groups) \\ \hline
2703 & - & - & 2669 & 2707 & \\ \hline - & - & 2715 & - & - & (overtone) \\ \hline
1719 & 1706 & 1707 & 1711 & 1716 & \(\forall\)(–C=O\({}_{\text{st}}\)) \\ \hline
1641 & 1616 & 1641 & 1643 & 1643 & \(\forall\)(–C=O) or \(\delta\) (O–H) in H\({}_{2}\)O \\ \hline
1592 & & - & - & 1581 & \(\forall\) (N–H) \\ \hline - & & - & 1457 & - & \\ \hline
1417 & 1414 & 1415 & 1417 & 142 & \(\delta\) (C–H) in alkenes \\ \hline
1341 & 1343 & 1340 & 1338 & 1338 & \(\delta\) (–OH) in C–OH group \\ \hline
1248 & 1243 & 1248 & 1248 & 1246 & \(\forall\) (C–O) acid stretching \\ \hline
1136 & - & 1134 & 1153 & 1148 & \(\forall\) (C–O) acid stretching and \(\delta\) (O–H) \\ \hline
1051 & 1048 & 1051 & 1053 & 1051 & deformation of acids \\ \hline
913 & - & - & 906 & 911 & \(\delta\) (O–H) deformation of acids, \\ \hline
839 & 837 & 886 & 873 & 868 & \\ \hline - & & 806 & 819 & 823 & \(\forall\) (C–O) in C–OH group Or \(\
u\) (C–C) in the carbohydrate structure and \(\delta\) (C–H) \\ \hline
782 & 775 & 788 & 785 & 777 & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: The location of the maxima of absorption bands FTIR with arrangement of appropriate vibration in terms of spectral 3750–700 cm\({}^{-1}\). Figure 3: Infrared spectra of the analysed juice samples: ACJ, PDF, RDF, PUF, and RUF in the spectral range from 700 to 3750 cm\({}^{-1}\).