## 3 Results and Discussion
### Impact of Ingredients and Processing Conditions on Selected Physical Properties
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Blueberry Addition** & **Screw Rotation** & **Moisture [\%]** & **WAI [g/gl]** & **WSI [\%]** & **Bulk Density** & **Durability [\%]** \\  & [\%] & **[rpm]** & 32 & 3.23 \(\pm\) 0.00 \({}^{\text{h}}\) & 8.23 \(\pm\) 0.01 \({}^{\text{h}}\) & 420.70 \(\pm\) 5.33 \({}^{\text{d}}\) & 98.10 \(\pm\) 0.12 \({}^{\text{c}}\) \\ \hline \multirow{3}{*}{0} & 60 & 36 & 3.90 \(\pm\) 0.01 \({}^{\text{s}}\) & 17.22 \(\pm\) 0.00 \({}^{\text{h}}\) & 384.64 \(\pm\) 4.40 \({}^{\text{h}}\) & 97.61 \(\pm\) 0.31 \({}^{\text{c}}\) \\ \cline{2-7}  & 100 & 32 & 3.99 \(\pm\) 0.01 \({}^{\text{s}}\) & 7.53 \(\pm\) 0.01 \({}^{\text{s}}\) & 425.23 \(\pm\) 13.31 \({}^{\text{d}}\) & 98.10 \(\pm\) 0.12 \({}^{\text{c}}\) \\ \cline{2-7}  & 100 & 36 & 4.07 \(\pm\) 0.01 \({}^{\text{h}}\) & 18.35 \(\pm\) 0.01 \({}^{\text{s}}\) & 416.72 \(\pm\) 5.40 \({}^{\text{d}}\) & 97.61 \(\pm\) 0.31 \({}^{\text{c}}\) \\ \hline \multirow{3}{*}{10} & 60 & 32 & 3.35 \(\pm\) 0.01 \({}^{\text{s}}\) & 10.71 \(\pm\) 0.01 \({}^{\text{s}}\) & 345.07 \(\pm\) 5.62 \({}^{\text{s}}\) & 96.69 \(\pm\) 0.31 \({}^{\text{s}}\) \\ \cline{2-7}  & 60 & 36 & 3.88 \(\pm\) 0.01 \({}^{\text{s}}\) & 8.23 \(\pm\) 0.01 \({}^{\text{s}}\) & 418.96 \(\pm\) 2.28 \({}^{\text{d}}\) & 97.61 \(\pm\) 0.31 \({}^{\text{s}}\) \\ \cline{2-7}  & 100 & 32 & 3.53 \(\pm\) 0.02 \({}^{\text{d}}\) & 16.00 \(\pm\) 0.01 \({}^{\text{s}}\) & 400.60 \(\pm\) 10.36 \({}^{\text{h}}\) & 96.69 \(\pm\) 0.31 \({}^{\text{s}}\) \\ \hline \multirow{3}{*}{30} & 60 & 32 & 3.51 \(\pm\) 0.01 \({}^{\text{d}}\) & 12.72 \(\pm\) 0.00 \({}^{\text{s}}\) & 494.39 \(\pm\) 2.34 \({}^{\text{s}}\) & 95.46 \(\pm\) 0.17 \({}^{\text{s}}\) \\ \cline{2-7}  & 36 & 36 & 3.66 \(\pm\) 0.01 \({}^{\text{s}}\) & 13.32 \(\pm\) 0.01 \({}^{\text{s}}\) & 510.17 \(\pm\) 1.98 \({}^{\text{s}}\) & 96.69 \(\pm\) 0.31 \({}^{\text{s}}\) \\ \cline{1-1} \cline{2-7}  & 100 & 32 & 3.21 \(\pm\) 0.01 \({}^{\text{s}}\) & 11.27 \(\pm\) 0.01 \({}^{\text{s}}\) & 526.16 \(\pm\) 4.87 \({}^{\text{h}}\) & 95.46 \(\pm\) 0.17 \({}^{\text{s}}\) \\ \hline \hline \end{tabular}  
*-k–means indicated with similar letters in columns do not differ significantly at \(\alpha\) = 0.05.  
\end{table} 
Table 5: Results of selected physical properties of snack pellets enriched with blueberry processed at variable conditions (\(n\) = 3 \(\pm\) SD). reduce expansion of the extrudate as it exits the die. Additionally, both increasing the moisture content and the screw speed under conditions with 30% blueberry addition led to a further increase in bulk density--from 494.4 kg/m\({}^{3}\) (60 rpm, 32% moisture) to 547.4 kg/m\({}^{3}\) (100 rpm, 36% moisture). This suggests that under these conditions, the structure of the extrudate becomes more compact and less expanded. [PERSON] et al. [39] reported analogous findings, where an increase in fresh beetroot content led to a decrease in bulk density of pellets. The highest bulk density of the pellet was recorded for the control sample at a screw speed of 100 rpm, while the lowest was observed for the pellet containing 20% of fresh beetroot processed at 60 rpm (466.5 kg/m\({}^{3}\) and 239.0 kg/m\({}^{3}\), respectively). The authors explained this by structure loosening caused by the presence of dietary fiber. In the present study, however, an opposite trend was observed. The addition of fresh blueberry, especially at 30%, resulted in a rise in bulk density. This was likely due to limited expansion caused by the presence of pectin and natural sugars in the fruit. In both studies, screw speed had a significant impact--higher speeds promoted an increase in density, which may be related to the formation of a more compact structure under intensified processing conditions. [PERSON] et al. [40] also reported comparable relationships between formulation, processing parameters and bulk density of snack pellets. They found that the highest bulk density values occurred in control samples without vegetable addition, processed at higher screw speed and lower moisture levels.