## 3 Results and Discussion
### Effects of the Grafting Degrees on the Physicochemical Properties of EWP
#### 3.1.2 The Grafting Degrees Changed the Structural Properties of EWP  
To further investigate the effects of the grafting degrees on the structure of EWP and the conjugate, samples were analyzed with FTIR spectroscopy. Figure 1 shows the FTIR spectra of the analyzed samples. The hydroxyl stretching band was represented by 3306 cm\({}^{-1}\), which was one of the characteristic structures of the sugar chains. Compared with EWP, EC\({}_{0}\) and the conjugated samples displayed higher absorption peaks here, indicating that the introduction of CMC-Na increased the hydroxyl content of EWP. The most distinctive spectral features of the protein are the amide I and II bands, which are distributed at approximately 1650 cm\({}^{-1}\) and 1540 cm\({}^{-1}\), respectively. When the protein was grafted by the grafting reaction, the incorporation of polysaccharides could increase the hydroxyl content of the protein, which was also accompanied by the consumption of amino acid \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Samples**} & \multirow{2}{*}{**DG (\%)**} & \multicolumn{4}{c}{**Color Differences**} & \multirow{2}{*}{**A\({}_{420}\) (10\({}^{-2}\))**} \\ \cline{3-3} \cline{5-6}  & & **L\({}^{*}\)** & & **a\({}^{*}\)** & **b\({}^{*}\)** & \\ \hline EWP & 0 \({}^{\text{e}}\) & 90.35 \(\pm\) 0.22 \({}^{\text{a}}\) & \(-\)0.08 \(\pm\) 0.02 \({}^{\text{e}}\) & 14.04 \(\pm\) 0.37 \({}^{\text{e}}\) & 0.30 \(\pm\) 0.03 \({}^{\text{f}}\) \\ EC\({}_{0}\) & 0.83 \(\pm\) 0.06 \({}^{\text{e}}\) & 88.77 \(\pm\) 0.19 \({}^{\text{b}}\) & 0.16 \(\pm\) 0.03 \({}^{\text{d}}\) & 15.59 \(\pm\) 0.44 \({}^{\text{d}}\) & 0.55 \(\pm\) 0.04 \({}^{\text{e}}\) \\ EC\({}_{12}\) & 8.0 \(\pm\) 0.4 \({}^{\text{d}}\) & 87.65 \(\pm\) 0.30 \({}^{\text{c}}\) & 0.26 \(\pm\) 0.05 \({}^{\text{c}}\) & 16.34 \(\pm\) 0.48 \({}^{\text{d}}\) & 1.94 \(\pm\) 0.05 \({}^{\text{d}}\) \\ EC\({}_{24}\) & 12 \(\pm\) 2 \({}^{\text{c}}\) & 86.57 \(\pm\) 0.47 \({}^{\text{d}}\) & 1.29 \(\pm\) 0.02 \({}^{\text{b}}\) & 17.53 \(\pm\) 0.29 \({}^{\text{c}}\) & 3.44 \(\pm\) 0.23 \({}^{\text{c}}\) \\ EC\({}_{36}\) & 16 \(\pm\) 3 \({}^{\text{b}}\) & 85.51 \(\pm\) 0.51 \({}^{\text{e}}\) & 2.15 \(\pm\) 0.07 \({}^{\text{a}}\) & 19.42 \(\pm\) 0.46 \({}^{\text{b}}\) & 4.53 \(\pm\) 0.17 \({}^{\text{b}}\) \\ EC\({}_{48}\) & 22 \(\pm\) 1 \({}^{\text{a}}\) & 84.12 \(\pm\) 0.41 \({}^{\text{f}}\) & 2.68 \(\pm\) 0.04 \({}^{\text{f}}\) & 21.31 \(\pm\) 0.87 \({}^{\text{a}}\) & 5.17 \(\pm\) 0.07 \({}^{\text{a}}\) \\ \hline \hline \end{tabular}  
* \({}^{\text{a}-d}\) Different letters in the same column indicate significant differences (\(p<\) 0.05).  
\end{table} 
Table 1: The grafting degree (DG), color differences, and absorbance at 420 nm (A\({}_{420}\)) of EWP and its conjugates. residues during the Maillard reaction. That altered the protein structure and tended to follow with changes in its functional properties, such as gel properties, emulsification properties, etc. Meanwhile, these changes were reflected in the spectrum as the migration, appearance, or disappearance of the bands [50]. The absorption peaks of the EWP amide I and II bands were at 1651 cm\({}^{-1}\) and 1531 cm\({}^{-1}\), respectively. These two bands of EC\({}_{0}\) hardly migrated and just increased in absorption intensity, which indicated that the CMC-Na at this time did not undergo a Maillard reaction with EWP, but rather, non-covalent binding. Meanwhile, the absorption peaks of samples EC\({}_{12}\), EC\({}_{24}\), EC\({}_{36}\), and EC\({}_{48}\) at the amide II band shifted from 1531 cm\({}^{-1}\) to 1541 cm\({}^{-1}\) as the grafting reaction proceeded, indicating the consumption of amino acid residues during the Maillard reaction [51]. The amide I band at 1661 cm\({}^{-1}\) represented the spectral overlap of C=O groups and was accompanied by in-plane -NH bending and the formation of C=N bonds [52].