Table 1.
Comparison of FT-IR absorption bands for assignment of cellulose, pectin and xyloglucan obtained in present experiment (column a) with previous results from refs [6, 20, 32–35] (column b). In column e, the residues of which spectra contains given frequency are denoted
| a | b | c | d | e |
|---|---|---|---|---|
| Frequency range (measured) | Frequency range (literature) | Assignment | Origin | Comment |
| 1740-1730 (P) | 1745-1740 | C = O stretching vibration of alkyl ester | Pectin | CWM and CDTA residue |
| – | 1650 | Amid I C-N stretching | Proteins | Mainly in Na2CO3 residue |
| – | 1640 | H-O-H bending vibration | Absorbed water | Mainly in Na2CO3 residue |
| 1600 (P) | 1630–1600 | COO- antisymmetric stretching | Polygalacturonic acid, carboxylate (pectin ester group) | Mainly CWM and CDTA residue |
| – | 1550 | Amid II N-H deformation | Proteins | |
| 1428 (C) | 1426 | CH2 symmetric bending | Cellulose | All residue, most intensive KOH residue |
| 1410 (P) | 1400 | COO- symmetric stretching | Carboxylate (pectin ester group) | CWM and CDTA residue |
| 1362 (XG, C) | 1370 | CH2 bending | Xyloglucan, Cellulose | All residues |
| 1330 (P) | 1320 | Ring vibration | Pectin | CWM and CDTA residue |
| 1313 (C) | 1317 | CH2 symmetric bending | Cellulose | KOH residue |
| 1268-1230 (P) | 1243 | C–O stretching | Pectin | CWM and CDTA residue |
| 1160 (C) | 1160 | O–C–O asymmetric stretching | Cellulose (glycosidic link) | All residues |
| 1143 (P) | 1146 | O–C–O asymmetric stretching | Pectin (glycosidic link) | All residues |
| 1147 (XG) | 1130 | O–C–O asymmetric stretching | Xyloglucan (glycosidic link) | None |
| 1103 (C) | 1115 | C–O stretching, C–C stretching | Cellulose (C2-O2) | KOH residue |
| 1093 (P) | 1100 | C–O stretching, C–C stretching | Pectin (ring) | None |
| 1071 (XG) | 1075 | C–O stretching, C–C stretching | Xyloglucan (ring) | None |
| Absence | 1042 | C–O stretching, C–C stretching | Xyloglucan (ring) | None |
| 1030 (C) | 1030 | C–O stretching, C–C stretching | Cellulose (C6-H2-O6) | |
| 1014 (P) | 1019 | C–O stretching, C–C stretching | Pectin (C2-C3, C2-O2, C1-O1) | KOH fraction |
| 1000 (C) | 1000 | C–O stretching, C–C stretching | Cellulose (C6-H2-O6) | Na2CO3 residue (potato) |
| 954 (P) | 960 | CO bending | Pectin | None |
| 941 (XG) | 944 | Ring vibration | Xyloglucan | None |
| 899 (C), 893 (XG) | 895 | C1-H bending | Xyloglucan, Cellulose (β-anomeric link) | All residues |
| 832 (P) | 833 | Ring vibration | Pectin | CDTA and NA2CO3 residue (potato) |
| Bands not assigned | ||||
| 1416 | XG | |||
| 1204 | C, XG | |||
| 1053 | C | |||
| 1019 | XG | |||
| 888 | P | |||