## 3 Results and Discussion
### Effect of the Pre-Treatment on the Properties of Dried Material  
During pre-treatment and drying, the physical properties, i.e., volume and density of the plant tissue, change. The volume changes depend mainly on the quality of the raw material subjected to the process, as well as the method of processing [29]. Shrinkage and density of dried carrot slices immersed in ethanol are summarized in Table 4. The shrinkage \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Type of Pre-Treatment** & **Shrinkage (-)** & **Density (g/cm\({}^{3}\))** & **Rehydration Rate (-)** & **Hygroscopic Properties (-)** \\ \hline untreated & 65.3 \(\pm\) 2.0 a & 0.79 \(\pm\) 0.10 a & 5.35 \(\pm\) 0.07 e & 5.34 \(\pm\) 0.02 bc \\
5 s EtOH & 69.4 \(\pm\) 3.9 a & 0.80 \(\pm\) 0.15 a & 5.78 \(\pm\) 0.02 cd & 6.08 \(\pm\) 0.12 a \\
15 s EtOH & 70.8 \(\pm\) 2.0 a & 0.83 \(\pm\) 0.21 a & 5.27 \(\pm\) 0.12 e & 5.65 \(\pm\) 0.16 b \\
60 s EtOH & 69.4 \(\pm\) 8.8 a & 0.87 \(\pm\) 0.03 a & 5.49 \(\pm\) 0.08 de & 4.60 \(\pm\) 0.03 d \\
180 s EtOH & 70.8 \(\pm\) 9.8 a & 0.92 \(\pm\) 0.29 a & 6.01 \(\pm\) 0.13 bc & 5.30 \(\pm\) 0.28 bc \\
5 s EtOH+US21 & 65.3 \(\pm\) 5.9 a & 0.84 \(\pm\) 0.01 a & 5.99 \(\pm\) 0.11 bc & 3.57 \(\pm\) 0.04 e \\
15 s EtOH+US21 & 76.4 \(\pm\) 5.9 a & 0.99 \(\pm\) 0.05 a & 6.23 \(\pm\) 0.03 ab & 6.09 \(\pm\) 0.18 a \\
60 s EtOH+US21 & 72.2 \(\pm\) 7.9 a & 1.02 \(\pm\) 0.45 a & 6.24 \(\pm\) 0.11 ab & 5.10 \(\pm\) 0.11 c \\
180 s EtOH+US21 & 73.6 \(\pm\) 2.0 a & 1.06 \(\pm\) 0.05 a & 6.37 \(\pm\) 0.08 a & 3.82 \(\pm\) 0.12 e \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Shrinkage, density, rehydration rate (after 3 h of rehydration), hygroscopic properties (after 72 h above NaCl solution) of dried carrot tissue pre-treated without and with ultrasound; error bars indicate \(\pm\) SD (standard deviation calculated from three repetitions). \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Type of Pre-Treatment** & **Drying Time to MR = 0.02** & **Dry Matter Content** & **Water Activity** \\  & **(min)** & **(\%)** & **(\%)** \\ \hline untreated & 100.8 \(\pm\) 0.3 c & 94.05 \(\pm\) 0.71 cd & 0.274 \(\pm\) 0.001 a \\
5 s EtOH & 99.2 \(\pm\) 0.3 d & 95.11 \(\pm\) 0.24 ab & 0.256 \(\pm\) 0.002 bc \\
15 s EtOH & 106.5 \(\pm\) 0.5 a & 94.60 \(\pm\) 0.32 abc & 0.265 \(\pm\) 0.001 ab \\
60 s EtOH & 104.7 \(\pm\) 0.8 b & 94.23 \(\pm\) 0.46 bcd & 0.272 \(\pm\) 0.001 a \\
180 s EtOH & 106.8 \(\pm\) 0.8 a & 95.07 \(\pm\) 0.30 abc & 0.251 \(\pm\) 0.001 c \\
5 s EtOH+US21 & 107.1 \(\pm\) 0.1 a & 92.19 \(\pm\) 0.24 e & 0.260 \(\pm\) 0.007 abc \\
15 s EtOH+US21 & 98.3 \(\pm\) 0.3 d & 95.46 \(\pm\) 0.08 a & 0.250 \(\pm\) 0.002 c \\
60 s EtOH+US21 & 104.2 \(\pm\) 0.3 b & 95.14 \(\pm\) 0.18 ab & 0.254 \(\pm\) 0.006 bc \\
180 s EtOH+US21 & 104.5 \(\pm\) 0.9 b & 93.34 \(\pm\) 0.33 d & 0.261 \(\pm\) 0.005 abc \\ \hline \hline \end{tabular}
\begin{tabular}{c} The results of two-way ANOVA \\ pre-treatment type \\ pre-treatment time \\ \end{tabular}
\end{table} 
Table 3: Drying time to MR = 0.02, dry matter content, water activity of dried carrot tissue pre-treated without and with ultrasound; error bars indicate \(\pm\) SD (standard deviation calculated from three repetitions). of the untreated dried carrot was 65.3 \(\pm\) 2.0%, while the density was equal to 0.79 \(\pm\) 0.10 g/cm\({}^{3}\). Both in the case of EtOH and EtOH+US treatments, there were no significant differences in these parameters of dried materials. Nevertheless, there was a noticeable tendency regarding the shrinkage and density, which increased in most cases in comparison to the untreated dried carrot. The higher shrinkage was observed for scallion stalk and apple treated with ethanol (with and without sonication) [9,26]. Furthermore, the density increased with the increasing time for both treatment variants in ethanol, and the two-factor analysis of variance showed the significant influence of the type of treatment on the material density (\(p\) = 0.022).