## 3 Results
### Water Holding Capacity (WHC) and Hygroscopicity  
Figure 6 shows the water holding capacity (WHC) of native potato starch and spray-dried starch powders [SD_3%, SD_5%]. Significant differences were found in the WHC of native potato starch and spray-dried starch powders. In detail, the SD_5% exhibited the highest WHC values, followed by the SD_3% powder, while native potato starch showed the lowest values. The WHC values of SD_3% powder were lower than those of SD_5% powders, indicating that there are fewer available sites for water retention. On the contrary, native potato starch exhibited the lowest WHC values, which could be attributed to the semi-crystalline structure of starch. [PERSON] et al. [21] reported that by increasing crystalline regions and decreasing amorphous regions, the water absorption capacity of modified sweet potato starch decreased due to limited water binding sites. [PERSON] et al. [65] reported that the water binding capacity of starch increased due to the disruption of secondary bonding, e.g., hydrogen bonds in the starch molecular chains during gelatinization. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Samples**} & **Bulk Density (g/mL)** & **Tapped Density (g/mL)** & **Carr Index (CI) (\%)** & **Hausner Ratio (HR)** \\ \hline Native & 0.51 & 0.59 & 13.18 & 1.16 \\ potato starch & (\(\pm\)0.08) a  & (\(\pm\)0.10) a  & (\(\pm\)0.10) ab  \\ \hline SD\_3\% & 0.14 (\(\pm\)0.01) b  & (\(\pm\)0.01) b  & (\(\pm\)5.43) a  & (\(\pm\)0.08) a  \\ \hline SD\_5\% & 0.15 (\(\pm\)0.01) b  & (\(\pm\)0.01) b  & (\(\pm\)0.01) b  \\ \hline SD\_5\% & 0.15 (\(\pm\)0.01) b  & (\(\pm\)0.01) b  & (\(\pm\)0.01) b  \\ \hline SD\_5\% & 0.15 (\(\pm\)0.01) b  & (\(\pm\)0.01) b  & (\(\pm\)0.01) b  \\ \hline SD\_5\% & 0.15 (\(\pm\)0.01) b  & (\(\pm\)0.01) b  & (\(\pm\)0.01) b  \\ \hline SD\_5\% & 0.15 (\(\pm\)0.01) b  & (\(\pm\)0.01) b  & (\(\pm\)0.01) b  & (\(\pm\)0.01) b  \\ \hline SD\_5\% & 0.15 (\(\pm\)0.01) b  & (\(\pm\)0.01) b  & (\(\pm\)0.01) b  \\ \hline SD\_5\% & 0.15 (\(\pm\)0.01) b  & (\(\pm\)0.01) b  & (\(\pm\)0.01) b  \\ \hline SD\_5\% & 0.15 (\(\pm\)0.01) b  & (\(\pm\)0.01) b  & (\(\pm\)0.01) b  \\ \hline SD\_5\% & 0.15 (\(\pm\)0.01) b  & (\(\pm\)0.01) b  & (\(\pm\)0.01) b  & (\(\pm\)0.01) b  \\ \hline SD\_5\% & 0.15 (\(\pm\)0.01) b  & (\(\pm\)0.01) b  & (\(\pm\)0.01) b  & (\(\pm\)0.04) b  \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Bulk density, tapped density, Carr index, and Hausner ratio of native potato starch, spray-dried potato starch powders at concentrations of 3% [SD_The hygroscopicity values of native potato starch and spray-dried starch powders at concentrations of 3% and 5% and relative humidities of 100%, 75.3%, and 68.8% are shown in Figure 7. The SD_3% powders exhibited the highest hygroscopicity values, followed by the SD_5% powders and native potato starch. Hygroscopicity is related to the hydrophilic nature of starch and the structure, particle size, and moisture content of the powders. The spray-dried powders exhibited a semi-crystalline to amorphous structure, while native starch was more crystalline. Since amorphous polymers tend to absorb moisture more easily than crystalline ones [66], the spray-dried powders are expected to show higher moisture sorption. Besides, the spray-dried powders had a smaller particle size, a larger surface area, and a more porous structure compared to the native potato starch, resulting in more interactions with water molecules. [PERSON] et al. [67] reported that smaller particles of lactose powder exhibited greater moisture sorption, which is related to the larger surface area and broader span of the particle size distribution material. As for the effect of moisture content, the higher the moisture content of the powders, the lower the hygroscopicity values, due to the increased water concentration gradient between the powders and the surrounding air. These findings are consistent with the results of [PERSON] et al.