# Dehumidified Air-Assisted Spray-Drying of Cloudy Beetroot Juice at Low Temperature
## 3 Results and Discussion
### Bulk Porosity  
The bulk porosity (\(\epsilon_{L}\)) of the obtained powders ranged from 60.33 \(\pm\) 1.66% to 73.96 \(\pm\) 1.13% (Table 2). The highest \(\epsilon_{L}\) values were obtained for the powders without the addition of a carrier (J90 and J130) and for the powder with the addition of powdered milk (JM130). No statistically significant influence of the drying temperature on the \(\epsilon_{L}\) of the powders was found. The lowest \(\epsilon_{L}\) was found for powders dried at a higher temperature with the addition of the carriers nutriose, maltodextrin, and kleptose (JN130, JMD130, and JK130). Similar values (63.3 \(\pm\) 0.7 to 72.5 \(\pm\) 0.92%) were obtained by [PERSON] et al. (2019), who dried rapeseed and honeybee honey using a traditional spray-drying method and with dehumidified air ([PERSON] et al., 2019). It can be concluded that the powders with the largest mean particle diameters had at the same time the highest \(\epsilon_{L}\), which was confirmed by the statistically significant Pearson coefficient (r = 0.874, Table 3). The higher the \(\epsilon_{L}\) of the material, the more air there is in the intermolecular spaces, which influences the degradation of valuable ingredients and reduces the storage stability of the powders ([PERSON] and [PERSON], 2015). Therefore, the powders without carriers (J90 and J130) and those with the addition of powdered milk (JM130) were the most durable and the best from the point of view of storage. The larger particle sizes resulted in lower bulk density and higher porosity. The powders with low loose bulk densities were characterized by high \(\epsilon_{L}\) (J130, JM130, J90, and J90c), which was confirmed by the statistically significant Pearson coefficient (r = \(-\)0.982, Table 3). Similar conclusions were reached by [PERSON] et al. (2012), who studied mango powders--the powders with large particle sizes had both a low bulk density and a high porosity ([PERSON] and [PERSON], 2015). A correlation  
\begin{table}
\begin{tabular}{c c c c c c c c c c} \hline  & \(T_{g}\) & **WC** & \(a_{uv}\) & \(D_{50}\) & \(D_{L}\) & \(D_{T}\) & HR & \(D_{ap}\) & \(\epsilon_{L}\) \\ \hline \(R_{P}\) & \(-\)0.400 & \(-\)0.604 & 0.152 & \(-\)0.201 & \(-\)0.168 & 0.078 & 0.838 \({}^{*}\) & 0.298 & 0.220 \\ \(T\) & & \(-\)0.089 & \(-\)0.649 & \(-\)0.594 & 0.697 & 0.579 & \(-\)0.415 & \(-\)0.313 & \(-\)0.718 \\ WC & & & \(-\)0.152 & 0.597 & \(-\)0.446 & \(-\)0.667 & \(-\)0.617 & \(-\)0.662 & 0.303 \\ \(a_{uv}\) & & & & 0.657 & \(-\)0.643 & \(-\)0.507 & 0.522 & 0.743 & 0.765 \({}^{*}\) \\ \(D_{50}\) & & & & & \(-\)0.884 \({}^{*}\) & \(-\)0.926 \({}^{*}\) & 0.017 & 0.127 & 0.874 \({}^{*}\) \\ \(D_{L}\) & & & & & & 0.956 \({}^{*}\) & \(-\)0.344 & \(-\)0.048 & \(-\)0.982 \({}^{*}\) \\ \(D_{T}\) & & & & & & & \(-\)0.061 & 0.136 & \(-\)0.905 \({}^{*}\) \\ HR & & & & & & & & 0.547 & 0.447 \\ \(D_{ap}\) & & & & & & & & & 0.226 \\ \hline \end{tabular}
\end{table}
Table 3: Pearson correlation coefficients (r) between the powder recovery (\(R_{P}\)), glass transition temperature (\(T_{g}\)), water content (WC), water activity (\(a_{uv}\)), median diameter (\(D_{50}\)), bulk loose density (\(D_{L}\)), bulk gapped density (\(D_{T}\)), Hausner ratio (HR), apparent density (\(D_{ap}\)), and loose bed porosity (\(\epsilon_{L}\)) of the beetroot powders; asterisks indicate statistically significant correlations (\(p<0.05\)).  
between \(\varepsilon_{L}\) and \(a_{w}\) was also observed and confirmed by a Pearson coefficient of r = 0.765 (Table 3). It can be concluded that the presence of the carrier and its type had a significant influence on the \(\varepsilon_{L}\) of the obtained powders.