# Thermal Properties of Ultrasound-Extracted Okra Mucilage
## 3 Results and Discussion
### Characterization of Thermal Properties  
#### 3.3.1 Differential Scanning Calorimetry (DSC)  
The data obtained from the analysis at different scanning speeds are presented in Table 2. The melting enthalpy, melting and initial temperatures, and glass transition temperatures obtained from the DSC thermograms are shown in Figure 3.  
Differential scanning calorimetry was employed for the purpose of determining various properties such as glass transition temperature, enthalpy, and phase change enthalpies. The glass transition temperatures of the samples obtained by extraction at different solid/solvent ratios and extraction times showed ranges between 41.65 and 5.96 \({}^{\circ}\)C, while the melting temperatures were in the range of 166.74-172.67 \({}^{\circ}\)C with \(\Delta\)H values between 158.2 and 225.6 j/g (Table 2). As shown in Figure 3, there are two endothermic peaks. The presence of bound moisture in okra gum is a well-known fact, and the initial peaks observed at approximately 140 \({}^{\circ}\)C during the process are indicative of the evaporation of bound moisture present in the okra gum sample. The evaporation temperature of bound moisture in okra gum is typically higher than the boiling temperature of water due to the presence of ionic bonds between water molecules and the polysaccharide linkages in the gum. As a result, a greater amount of heat is required to break these bonds and release the bound moisture [31]. The appearance of secondary peaks in the thermal analysis of the okra gum samples indicates the melting of the crystalline phase within the gum. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline  & \multicolumn{6}{c}{**UAEOP Time**} \\ \cline{3-10}  & \multicolumn{6}{c}{**10 min**} \\ \cline{3-10}
**UAGOP** & **Ratios** & **1/10** & **1/25** & **1/30** & **1/50** & **1/10** & **1/25** & **1/30** & **1/50** \\ \hline \(\Delta\)H (Hg)\({}^{*}\) & 185.4 \(\pm\) 9.90 \({}^{\circ}\) & 185 \(\pm\) 3.89 \({}^{\circ}\) & 224  
The sample obtained using a solid/solvent ratio of 1/10 and an ultrasound duration of 5 min exhibited the highest melting temperature among all the samples tested. The  
Figure 3: DSC thermograms of okra polysaccharides obtained under different ultrasound-assisted extraction conditions. statistical analysis revealed that there were significant differences in the melting temperatures of samples obtained using 1/10 and 1/25 solid/solvent ratios at a 5-min ultrasound duration. However, no significant differences were observed in the melting temperatures when the solid/solvent ratios were changed, and the ultrasound duration was increased to 10 min; therefore, increasing the ultrasound time did not make a significant difference in the melting temperature. Although there was no significant variation in the ratios of solids to solvents when the extraction time was five minutes, there was a statistically significant increase in the glass transition temperatures when the time was extended to ten minutes. This suggests that the material's thermal stability is enhanced by augmenting its viscous structure at higher temperatures. Thus, extending the extraction time might result in physical and chemical transformations in the food's molecular structure. The relationship between the solid/liquid ratio and the glass transition temperature was noted to be time dependent. Specifically, as the solid/liquid concentration ratio decreases, the glass transition temperature tends to increase. The highest glass transition temperature (52.96 \(\pm\) 1.37) was observed in the sample extracted for 10 min with a solid/liquid ratio of 1/50. A higher glass transition temperature has positive effects on the stiffness, hardness, and dimensional stability of the product, which is advantageous for determining processing conditions and end-use properties in the industry.