# Some Aspects of the Modelling of Dried Red Beets Rehydration Process
## 3 Results and Discussion
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Model No.** & **Model Name** & **Parameter Equation** \\ \hline (1) & [PERSON] & \(A_{1}=0.03954{v_{d}}^{2}+0.0004{T_{r}}^{2}-0.005{T_{d}}{v_{d}}+0.01231{T_{d} }L-0.0004{T_{d}}{T_{r}}-0.0089{T_{r}}\) \\  & & \(A_{2}=-0.103+0.06538L-0.0086{L}^{2}\) \\ \hline (2) & Lewis (Newton) & \(k=0.00012{T_{d}}+0.0065{v_{d}}-0.0006{v_{d}}^{2}+3.4\times 10^{-6}{T_{r}}^{2}-0.001{v_{ d}}L-2\times 10^{-5}{T_{r}}\) \\ \hline (3) & Henderson–Pabis & \(\begin{array}{c}k=0.00229{v_{d}}+0.005L-0.0004{v_{d}}^{2}-0.0009{L}^{2}+2.3 \times 10^{-6}{T_{r}}^{2}\\ a=2.38536-0.0174{v_{d}}-0.8424L+0.00209{v_{d}}^{2}+0.11246{L}^{2}\end{array}\) \\ \hline (4) & Page & \(k=-0.6793+0.01179{v_{d}}+0.41076L-0.0014{v_{d}}^{2}-0.054{T^{2}}+1.2\times 1 0^{-5}{T_{r}}^{2}-0.0001{T_{r}}\) \\  & \(n=5.83176-2.9365L+0.00611{v_{d}}^{2}+0.39838{L}^{2}-3\times 10^{-5}{T_{d}}{T_{r}}-0.02 18{v_{d}}L\) \\ \hline (5) & Modified Page & \(k=0.00013{v_{d}}+0.00861L-0.0014{L}^{2}\) \\  & \(n=0.8561-0.026{v_{d}}+0.00401{L}^{2}-10^{-5}{T_{r}}^{2}\) \\ \hline \hline \end{tabular}
\end{table} 
Table 8: Parameter equations for the models adopted to changes of moisture content during rehydration of dried red beets. [PERSON], [PERSON] ([PERSON]), and [PERSON], enabled the prediction of the moisture content increase during the rehydration of dried red beets, considering the influence of \(T_{d}\), \(v_{d}\), \(L\), and \(T_{r}\). The Henderson-Pabis model and modified Page models can be adopted for prediction only when the drying air temperature is not very important for the prediction for the investigated process. Table 9 shows the results of statistical analyses on the modelling of mass, volume, dry matter, and moisture content changes in the dried red beets during rehydration, where model parameters are expressed with equations presented in Tables 5-8. As far as the mass gain during the rehydration of dried red beets is concerned, it can be suggested that the [PERSON] (Newton), Henderson-Pabis, and modified Page models fitted quite well to the experimental data for mass gain. The values of the applied statistical test criteria for the three mentioned models ranged from 0.9070 to 0.9966 for R\({}^{2}\), from 0.9021 to 0.9964 for adjusted R\({}^{2}\), and from 0.0236 to 0.1076 for RMSE. It can be noticed, however, that among the discussed models, the modified Page model gave the best values out of the considered test methods (R\({}^{2}\) = 0.9647-0.9966, adjusted R\({}^{2}\) = 0.9628-0.9964, RMSE = 0.0236-0.0897), and therefore, it can be recommended as the most acceptable for describing mass gain kinetics during the rehydration of dried red beets. It can be admitted that the [PERSON], modified Page, and the [PERSON] models performed well regarding the volume increase. The values of the used statistical test methods changed from 0.8888 to 0.9948 for the R\({}^{2}\), from 0.8830 to 0.9945 for the adjusted R\({}^{2}\), and from 0.0213 to 0.8878 for the RMSE. Comparing the obtained results, it can be stated that the mentioned [PERSON] model gave the most acceptable results of the statistical analyses, as far as the volume increase during the rehydration of dried red beets is concerned (R\({}^{2}\) = 0.9349-0.9948, adjusted R\({}^{2}\) = 0.9314-0.9945, RMSE = 0.2213-0.0972). Taking into account the values of R\({}^{2}\) (0.9104-0.9963), adjusted R\({}^{2}\) (0.9057-0.9961), and RMSE (0.0161-0.1684), it can be decided that three models, namely, [PERSON], [PERSON] (Newton), and [PERSON], described the course of dry matter loss during the rehydration of dried red