## 3 Results
### Physical Properties of Corn-Based Crisps Supplemented with Fruits
A more intensive decrease of EI was obtained, however, if 5% of mulberry fruit was in the recipe, but further increase of mulberry content led to limited expansion of the supplemented crisps. This is also visible in the results of bulk density, which was lower than that for apple addition, with maximum BD = 206.79 kg/m\({}^{3}\) for snacks with 20% of additive extruded at the lowest screw speed, while very small differences were found between 15 and 20% of fruit additive. As reported by [PERSON] et al. [15], fruit powders may compete for moisture during the extrusion process, and this affects the degree of gelatinization and, therefore, the degree of expansion and the bulk density. They found DB values ranging from 209 to 311 kg/m\({}^{3}\) when adding dried fruits in amounts of 11% to a wheat-corn-potato-milk powder recipe (50 kg/m\({}^{3}\) for control). According to [PERSON] et al. [37], the presence of sugar and soluble fiber that absorb moisture in dried fruit may affect the expansion capability of the extrudates. We found, however, that the application of various amounts of white mulberry had only a very slight effect on WSI, and these snacks showed similar results of WSI (from 16.19% to 20.95%) with an ambiguous effect of additive level and \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Fruit** **Amount [\%]** & **Screw Speed** **[rpm]** & **EI [-]** & **BD [kg/m\({}^{3}\)]** & **WAI [g/g]** & **WSI [\%]** \\ \hline \multirow{3}{*}{5} & 80 & 3.74 \(\pm\) 0.04 & 53.98 \(\pm\) 0.41 & 5.16 \(\pm\) 0.05 & 18.10 \(\pm\) 0.67 \\  & 100 & 3.64 \(\pm\) 0.02 & 51.14 \(\pm\) 0.25 & 5.26 \(\pm\) 0.07 & 18.10 \(\pm\) 1.35 \\  & 120 & 4.35 \(\pm\) 0.04 & 42.50 \(\pm\) 0.29 & 4.88 \(\pm\) 0.22 & 18.10 \(\pm\) 1.78 \\ \hline \multirow{3}{*}{10} & 80 & 2.85 \(\pm\) 0.06 & 60.68 \(\pm\) 0.23 & 4.69 \(\pm\) 0.06 & 15.24 \(\pm\) 1.78 \\  & 100 & 2.90 \(\pm\) 0.06 & 54.87 \(\pm\) 0.50 & 4.71 \(\pm\) 0.01 & 18.10 \(\pm\) 1.35 \\  & 120 & 3.35 \(\pm\) 0.05 & 47.92 \(\pm\) 0.39 & 4.74 \(\pm\) 0.05 & 15.71 \(\pm\) 3.50 \\ \hline \multirow{3}{*}{15} & 80 & 2.61 \(\pm\) 0.03 & 71.19 \(\pm\) 0.43 & 4.50 \(\pm\) 0.06 & 18.57 \(\pm\) 0.00 \\  & 100 & 2.79 \(\pm\) 0.05 & 62.05 \(\pm\) 0.23 & 4.57 \(\pm\) 0.02 & 15.71 \(\pm\) 1.17 \\  & 120 & 2.80 \(\pm\) 0.03 & 56.99 \(\pm\) 0.40 & 4.40 \(\pm\) 0.01 & 17.63 \(\pm\) 0.67 \\ \hline \multirow{3}{*}{20} & 80 & 1.99 \(\pm\) 0.03 & 107.39 \(\pm\) 0.67 & 3.58 \(\pm\) 0.03 & 17.62 \(\pm\) 0.65 \\  & 100 & 1.87 \(\pm\) 0.06 & 111.89 \(\pm\) 0.48 & 3.57 \(\pm\) 0.05 & 18.57 \(\pm\) 2.33 \\ \cline{1-1}  & 120 & 1.83 \(\pm\) 0.05 & 115.43 \(\pm\) 0.46 & 3.41 \(\pm\) 0.05 & 17.52 \(\pm\) 0.77 \\ \hline \hline \end{tabular} El—expansion index; BD—bulk density; WAI—water absorption index; WSI—water solubility index; results are presented as mean \(\pm\) standard deviation.  
\end{table} 
Table 7: Physical properties of corn-based crisps supplemented with blackberry powder. applied screw speed. Of note, WAI of the tested snacks was higher than control sample if 5 and 10% of additive was used, and more mulberry powder limited water absorption of crisps. The next fruit used in the crisps recipes was goji berry powder. The physical properties of snacks obtained with addition of 5-20% of goji powder are presented in Table 5.  
The tested snacks were very well expanded and light in weight when the amount of goji berry powder was up to 10%, and the differences in EI of crisps were very small at 5 and 10% of goji berry and lowered significantly with increasing amount of powdered fruit. Due to good expansion, the bulk density of the mentioned samples was very low, up to 74.72 kg/m\({}^{3}\) at 10% of additive. Higher shear forces applied to the fruit increased BD to more than triple in samples with 20% of goji powder, and the results were very similar to samples supplemented with apple powder. Water absorption of supplemented snacks was higher than control once the amount of additive was 5 to 10%.