## 3. Results and Discussion
### FT-IR Spectroscopy of FPs  
The FT-IR spectra of four kinds of FPs are shown in Figure 2A. FPs obtained by different drying methods showed absorption peaks at 3407 cm\({}^{-1}\), 2938 cm\({}^{-1}\), 1743 cm\({}^{-1}\), 1639 cm\({}^{-1}\), 1423 cm\({}^{-1}\), 1018 and 1101 cm\({}^{-1}\). The broad absorption peak at about 3407 cm\({}^{-1}\) is attributed to O-H stretching vibration, while the narrow weak absorption peak at about 2938 cm\({}^{-1}\) is attributed to C-H stretching vibration. [PERSON] et al. [6] also found these two bands when studying the extraction optimization of fig polysaccharides, which are considered to be the characteristic peak groups of polysaccharides. In addition, the relatively weak 1743 cm  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Molecular Weight (Da)** & **FPF** & **FPV** & **FPFI** & **FPH** \\ \hline Number average molecular weight (Mn) & \(8.572\times 10^{4}\) & \(1.088\times 10^{5}\) & \(5.047\times 10^{4}\) & \(1.124\times 10^{5}\) \\  & (\(\pm 0.959\%\)) \({}^{\text{c}}\) & (\(\pm 1.982\%\)) \({}^{\text{b}}\) & (\(\pm 1.145\%\)) \({}^{\text{d}}\) & (\(\pm 1.245\%\)) \({}^{\text{a}}\) \\ Peak molecular weight (Mp) & \(4.240\times 10^{4}\) & \(6.484\times 10^{4}\) & \(4.711\times 10^{4}\) & \(6.792\times 10^{4}\) \\  & (\(\pm 1.036\%\)) \({}^{\text{b}}\) & (\(\pm 0.805\%\)) \({}^{\text{a}}\) & (\(\pm 1.621\%\)) \({}^{\text{b}}\) & (\(\pm 1.005\%\)) \({}^{\text{a}}\) \\ Weight average molecular weight (Mw) & \(1.457\times 10^{5}\) & \(1.664\times 10^{5}\) & \(8.473\times 10^{4}\) & \(1.798\times 10^{5}\) \\  & (\(\pm 1.456\%\)) \({}^{\text{c}}\) & (\(\pm 1.749\%\)) \({}^{\text{b}}\) & (\(\pm 2.034\%\)) \({}^{\text{d}}\) & (\(\pm 1.469\%\)) \({}^{\text{a}}\) \\ Mw/Mn & \(1.700\pm 0.01\) \({}^{\text{a}}\) & 1.530 \(\pm\) 0.02 \({}^{\text{b}}\) & 1.679 \(\pm\) 0.02 \({}^{\text{a}}\) & 1.599 \(\pm\) 0.03 \({}^{\text{b}}\) \\ \hline \hline \end{tabular} Note: Data are expressed as means \(\pm\) SD (\(n=3\)). Different superscript lowercase letters (a–d) are significantly different (\(p<0.05\)).  
\end{table}
Table 3: Effects of different drying methods on molecular weight distribution.  
and 1639 cm\({}^{-1}\) are asymmetric and symmetric telescopic vibrations with C=O. [PERSON] et al. [24] also reported that these two spectra were considered to be the characteristic peak groups of uronic acid in the structural characterization of fig polysaccharide. The absorption peak at 1423 cm\({}^{-1}\) is the variable angular vibration of C-H, which is attributed to the molecular modification of polysaccharides by drying. The bands at 1018 cm\({}^{-1}\) and 1101 cm\({}^{-1}\) are C-O-C glycosidic bond stretching vibrations, indicating that the polysaccharide is in the form of pyranose. Based on FT-IR spectroscopy analysis, the four FPs have similar chemical groups, indicating that different drying methods have no obvious influence on the skeleton structure of FPs. [PERSON] et al. [40] studied the effects of different drying methods on bitter gourd polysaccharides and the results showed that different dried polysaccharides have similar structural characteristics. This is consistent with our findings.