Table 2.
Probable hydrogen bonds between Speckled Sugar bean protein (0.5%) and xanthan gum at different pH values based on FTIR spectra
| pH | Xanthan (%) | |||
|---|---|---|---|---|
| 0 | 0.1 | 0.2 | 0.3 | |
| 3 | 3294 cm−1 (NH stretching) |
3299 | 3300 | 3397 (xanthan OH) |
| 1654 cm−1 (C = O stretching) |
1653 | 1654 | 1654 | |
| 1541 cm−1 (CN streching, NH bending) |
1561 | 1540 | 1560 | |
| 1240 cm−1 (CN streching, NH bending) |
1233 | 1240 | 1241 | |
| 670 cm−1 (out of plane NH bending) |
671 | 602 (xanthan COO−) | 603 (xanthan COO−) | |
| Probable hydrogen bond | No hydrogen bond | Protein NH–xanthan COO− | Protein NH–xanthan COO− protein NH–xanthan OH |
|
| 5 | 3301 cm−1 (NH stretching) |
3411 | 3316 | 3316 |
| 1655 cm−1 (C=O stretching) |
1654 | 1653 | 1654 | |
| 1546 cm−1 (CN streching, NH bending) |
1546 | 1556 | 1551 | |
| 1245 cm−1 (CN streching, NH bending) |
1245 | 1243 | 1242 | |
| 662 cm−1 (out of plane NH bending) |
603 (xanthan COO−) | 665 | 671 | |
| Probable hydrogen bond | Protein NH-xanthan OH protein NH-xanthan COO− |
No hydrogen bond | No hydrogen bond | |
| 7 | 3300 cm−1 (NH stretching) |
3302 | 3300 | 3428 (xanthan OH) |
| 1654 cm−1 (C=O stretching) |
1654 | 1653 | 1653 | |
| 1544 cm−1 (CN streching, NH bending) |
1544 | 1546 | 1561 | |
| 1240 cm−1 (CN streching, NH bending) |
1245 | 1242 | 1241 | |
| 674 cm−1 (out of plane NH bending) |
606 (xanthan COO−) | 602 (xanthan COO−) | 672 | |
| Probable hydrogen bond | Protein NH-xanthan COO− | Protein NH-xanthan COO− | Protein NH-xanthan OH | |