## 3 Results
### Moisture and Particle Size Analysis  
Moisture content is an important factor that affects the quality and stability of the powder [51]. According to Figure 4a, native potato starch exhibited the highest moisture content values. In detail, the moisture content of native starch was significantly higher than that of the spray-dried starch powders. That is, at an inlet temperature of 220 \({}^{\circ}\)C, the temperature gradient between the hot air and liquid feed is increased, which in turn would reduce the final moisture content [52]. The results showed that the spray-dried powders with 5% starch concentration had a higher moisture content compared to those with 3% starch concentration. This is likely assigned to the increased viscosity of the starch solution, which affects droplet formation and the moisture evaporation during drying. Probably, the increased viscosity of the SD_5% starch solution caused the formation of larger droplets with a lower surface area, reducing moisture evaporation and resulting in greater retention in the final products. On the contrary, in the case of the SD_3% powder, smaller droplets were formed with a higher surface area, favoring the evaporation of water. Figure 3: Optical images of native potato starch and spray-dried potato starch powders at concentrations of 3% [SD_3%] and 5% [SD_5%]. Red arrows indicate the spherical granules in the native potato starch and the wrinkled granules in spray-dried starch powders. During atomization, feed solutions with high viscosity generally result in the formation of larger particles, as postulated by [PERSON] et al. [53]. However, it should be noted that the hydrophilic nature of starches prevents the evaporation of water during drying. Thus, it can be implied that the moisture content of the spray-dried powders could be affected by their particle size and hydrophilic nature. The particle size distribution of the native potato starch and spray-dried starch powders at concentrations of 3% and 5% are presented in Figure 4b, while the particle size parameters, including span, uniformity, specific surface area, D(4.3), D(3.2), D(0.1), D(0.5), and D(0.9), are shown in Table 2. Statistical analysis revealed significant differences among the particle size parameters of the native potato starch and spray-dried powders. All samples exhibited different span and uniformity values, indicating that the gelatinization and spray-drying processes resulted in the formation of particles with non-uniform sizes. Figure 4: Moisture content (**a**) and particle size distribution (**b**) of native potato starch and spray-dried potato starch powders at concentrations of 3% [SD_3%], and 5% [SD_5%]. The vertical lines indicate the 95% confidence interval of the means, derived from the error mean square of the analysis of variance. Groups labeled with different letters are significantly different according to [PERSON]’s pairwise comparison of means (\(p\) < 0.05). The D(4.3) and D(0.5) values showed that the native starch had the largest particles, while the SD_3% powder had the smallest particles. Similar trends were also observed in the parameters of D(0.1), D(0.5), and D(0.9). Smaller particles, as observed in the spray-dried powders, have a larger surface area, while the larger particles of native starch have a smaller surface area. This was further verified by the high surface area per unit weight values in the spray-dried samples compared to those in the native starch. Besides, SD_5% had lower span values compared to SD_3%, indicating a narrower distribution. The rapid evaporation of water during the spray-drying process likely led to the formation of granules with a wider distribution of particle sizes. The differences in particle size parameters between the native potato starch and spray-dried powders are probably related to the starch concentration and viscosity of starch solution. Thus, the increased feed viscosity could result in increased droplet size distribution and the production of larger particles [54].