## 3 Results and Discussion
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Product** & **Wettability, s** & **Insolubility** & **Loose Bulk** & **Tapped Bulk** & **Carr Index, \%** & **Hausner Ratio** \\  & **Index, cm3** & **Density, g/cm3** & **Density, g/cm3** & **Density, g/cm3** & **Carr Index, \%** & **Hausner Ratio** \\ \hline MCC & \textgreater{}180 & 10.75 \(\pm\) 0.12 \({}^{\text{b}}\) & 0.16 \(\pm\) 0.01 \({}^{\text{a}}\) & 0.20 \(\pm\) 0.01 \({}^{\text{a}}\) & 20.03 \(\pm\) 0.82 \({}^{\text{b}}\) & 1.25 \(\pm\) 0.01 \({}^{\text{b}}\) \\ SPC & \textgreater{}180 & 0.10  
bed. Loose bulk density denotes the volume of a powder, including the volume of void spaces between particles, whereas tapped density is the density of a powder where small particles enter voids between large particles, decrease the powder's volume and increase its density [10]. Flow properties were assessed by calculating the Hausner ratio and the Carr index based on loose and tapped bulk density (Table 2). High-protein milk powders were classified based on the calculated values of the Carr index (CI) and the Hausner ratio (HR) [22]. Powders with a higher Hausner ratio were more cohesive, whereas powders with a lower Carr index were more flowable (free-flowing). An analysis of Carr index values revealed that MCC and SPC had fairly good flow properties (20-35%). Commercial whey protein powders were fairly flowable, whereas CH was characterized by very good flowability. In turn, the calculated values of the Hausner ratio demonstrated that all analyzed high-protein milk powders were moderately cohesive (1.2-1.4), except CH, which was characterized by low cohesiveness. These results confirmed that increased protein content and reduced lactose content contribute to strong intermolecular interactions in dairy powders, and enhance cohesive forces that determine flowability [27]. According to [PERSON] et al. [10], the cohesiveness, flowability, and reconstitution properties of powders are determined by, among other things, particle shape, surface, size, hygroscopicity, and porosity. The results of particle size measurements revealed that the MCC preparation was characterized by the largest particles (d\({}_{32}\), 52 um). The remaining high-protein milk powders were divided into two groups based on particle size. The first group was characterized by larger particles (\(\geq\)35 um), and it included CH, WPC, and SPC. The second group was characterized by smaller particles (\(\leq\)20 um), and it comprised WPH and WPI (Table 3). Despite a high particle dispersion, the WPH was characterized by greater differences in particle size, as indicated by high SPAN values and differences between d\({}_{32}\) and d\({}_{43}\). Particle size distribution was more uniform in the remaining high-protein milk powders (Table 3). The large particle sizes of high-protein milk powders result from the size of the concentrate drops dispersed during spray drying, and are also related to their cohesiveness. This is particularly evident in the case of MCC, which is larger in size and has higher values of cohesiveness and flowability than the commercial CH preparation. The micrograph analysis confirmed the results of particle size measurements and demonstrated that most of the examined high-protein milk powders, regardless of protein type, contained particles with a smooth surface (Figure 2). \begin{table}
\begin{tabular}{c c c c} \hline
**Product** & **D32, μm** & **D43, μm** & **SPAN** \\ \hline MCC & 52.04 \(\pm\) 3.96  & 2.00 \(\pm\) 0.07  & 81.59 \(\pm\) 3.00  \\ \hline WPC & 36.95 \(\pm\) 1.95  & 1.73 \(\pm\) 0.10  & 81.33 \(\pm\) 3.33  \\ \hline WPH & 10.25 \(\pm\) 1.75  & 3.75 \(\pm\) 0.12  & 39.15 \(\pm\) 3.85  \\ \hline \end{tabular}
\end{table} 
Table 3: Diameter and particle size distribution of high-protein milk powders. The morphology of powder particles influences a powder's reconstitution characteristics and flowability.