## 3 Results
### Moisture Sorption Characteristics of OD-Treated Cherry Tomato and Spinach-Based RTE Products
#### 3.1.2 OD-Treated Spinach-Based RTE Product  
OD-treated spinach serves as the foundational green base, contributing a vibrant and nutrient-rich element to the salad. Its osmotic dehydration process ensures moisture removal while preserving essential nutrients, enhancing the spinach's shelf stability without compromising its nutritional value. Complementing the spinach, osmotically dehydrated and air-dried feta trimmings bring a distinctive tangy and creamy flavor profile, infusing the salad with a hint of Mediterranean-inspired richness. The combination of these feta trimmings with ground peanuts adds a satisfying textural dimension, with the peanuts providing a crunchy contrast to the softer spinach and feta components.  
The resulting equilibrium curves at 25 \({}^{\circ}\)C obtained at different water activities for the three ingredients of OD-treated spinach-based RTE product are presented in Figure 3. The dependence of moisture content from water activity was mathematically modeled using the GAB equation (Equation (1)) and the model parameters are presented in Table 3. The GAB model was reported to describe the water vapor adsorption isotherms of dehydrated/dried fruits/vegetables (including dried spinach) [41]. The results revealed that the three ingredients exhibited different characteristics in terms of moisture transfer. The moisture content of the OD-spinach material remained relatively high within the whole range of a\({}_{\text{w}}\) values studied, namely between 2 and 5 g/g DW. On the other hand, both peanuts and dehydrated cheese had moisture contents ranging between 0.1 and 0.9 g/g DW. This shows that peanuts are much more hydrophobic compared to the other two materials, which is expected due to their high oil content (up to 50%).  
\begin{table}
\begin{tabular}{l c c c c c} \hline  & & & \multicolumn{3}{c}{**GAB Model Parameters**} & **Predicted** \\ \cline{4-6}
**Ingredient** & **Initial \(a_{w}\)** & **Equilibrium \(a_{w}\)** & \(W_{m}\) (g/g) & \(C\) (-) & \(K\) (-) & **Equilibrium** \\ \hline
**OD-Treated Tomato** & 0.920 \(\pm\) 0.002  & 0.446 \(\pm\) 0.005  & 4.30 \(\pm\) 0.11  & 0.908 \(\pm\) 0.012  & \\
**OD-Treated and Air-Dried Cheese** & 0.533 \(\pm\) 0.002  & 0.852 \(\pm\) 0.002 & 0.116 \(\pm\) 0.002  & 4.04 \(\pm\) 0.09  & 0.939 \(\pm\) 0.010  & 0.859 \(\pm\) 0.001  & 0.859 \(\pm\) 0.001  & 0.859 \(\pm\) 0.001  & 0.859 \(\pm\) 0.001  & & \\
**Air-Dried Olives** & 0.267 \(\pm\) 0.001  & 2.25 \(\pm\) 0.04  & 0.03 \(\pm\) 0.01  & 0.835 \(\pm\) 0.009  \\ \hline \end{tabular}  
Mean value \(\pm\) standard deviation. Different superscript letters in the same column indicate significant differences between means as calculated using [PERSON]’s multiple range test for a significance level of \(p=0.05\).  
\end{table}
Table 2: Water activity characteristics of the ingredients for the OD-treated tomato-based RTE product before mixing and at equilibrium. The predicted equilibrium value results from the water mass balances combined with the fitting of the GAB equation to the experimental data.  
Upon mixing the three ingredients of the final product, moisture is transferred between the ingredients. Specifically, it was expected that OD-spinach would lose water while peanuts and feta would gain moisture, to finally reach an equilibrium water activity. Given the product's formulation, the initial water content of each ingredient, the initial water activity values, and the apparent moisture equilibrium curves, it was possible to estimate the final equilibrium water activity of the product (Table 3). This value was also confirmed by experimental measurements after the equilibrium had been established. As observed by the final values presented in Table 3, the water activity of the product was significantly lower (0.754) than the respective water activity of the OD-treated spinach (0.930).