## 3 Results
### Shelf-Life Determination and Modeling of OD-Treated Cherry Tomato and Spinach-Based RTE Products  
#### 3.5.1 OD-Treated Tomato-Based RTE Product  
The two shelf-life-defining characteristics for the tomato-based product were considered to be microbial growth and sensory deterioration. As discussed, microbial growth was severely retarded due to the various hurdles present in the product. This becomes evident in the shelf-life curves presented in Figure 8a, where the curve corresponding to the shelf life of the product based on sensory deterioration appears to be shifted towards lower storage temperatures. Therefore, the shelf life of the product was limited by sensory deterioration. This is not uncommon, since other physicochemical alterations often precede microbial growth, especially in dehydrated products [47].  
In Table 7, the shelf life of the RTE tomato-based product is presented and compared with the shelf life of untreated tomatoes, as calculated from the results of the experiments on the untreated tomatoes. It is observed that at 4 \({}^{\circ}\)C, the shelf life of the OD-tomato-based RTE product was calculated to be 54.0 d compared to the 13.8 d of the shelf life of the respective untreated tomato-based RTE product. This shelf life extension achieved through applying OD to RTE product materials is due to the significant reduction in the water activity that led to the significant delay of microbial growth.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline  & \multicolumn{2}{c}{**OD-Tomato-Based RTE Product**} & \multicolumn{2}{c}{**OD-Spinach-Based RTE Product**} \\ \hline \multirow{2}{*}{**Storage Temperature (\({}^{\circ}\)C)**} & \multirow{2}{*}{**Shelf Life (d)**} & \multicolumn{2}{c}{**Estimated Shelf Life with**} \\  & & **Untreated Tomatoes (d)** & & **Shelf Life (d)** \\ \hline
4 & 54.0 \(\pm\) 5.3 \({}^{\mathrm{a}}\) & 13.8 \(\pm\) 0.9 \({}^{\mathrm{c}}\) & 36.3 \(\pm\) 4.0 \({}^{\mathrm{a}}\) & 4.7 \(\pm\) 0.3 \({}^{\mathrm{d}}\) \\
8 & 43.2 \(\pm\) 3.8 \({}^{\mathrm{b}}\) & 7.2 \(\pm\) 0.4 \({}^{\mathrm{d}}\) & 19.1 \(\pm\) 3.2 \({}^{\mathrm{b}}\) & 4.0 \(\pm\) 0.3 \({}^{\mathrm{d}}\) \\
12 & 17.7 \(\pm\) 3.7 \({}^{\mathrm{c}}\) & 3.8 \(\pm\) 0.2 \({}^{\mathrm{de}}\) & 9.8 \(\pm\) 1.8 \({}^{\mathrm{c}}\) & 3.2 \(\pm\) 0.2 \({}^{\mathrm{d}}\) \\
20 & 7.3 \(\pm\) 1.2 \({}^{\mathrm{d}}\) & 1.0 \(\pm\) 0.1 \({}^{\mathrm{e}}\) & 5.0 \(\pm\) 1.2 \({}^{\mathrm{d}}\) & 1.4 \(\pm\) 0.1 \({}^{\mathrm{e}}\) \\ \hline \hline \end{tabular}  
* Different superscript letters indicate significant differences between means of shelf life \(\pm\) standard deviation as calculated using [PERSON]’s multiple range test for a significance level of \(p\) < 0.05.  
\end{table}
Table 7: Calculated shelf life of the tomato- and spinach-based RTE product for each storage temperature studied. Values are compared with the estimated shelf-life values of the shelf life of the untreated tomatoes.  
Figure 8: Shelf-life (SL) curves of the developed (**a**) tomato- (based on microbial growth and sensory criteria) and (**b**) spinach- (based on sensory criteria) based RTE products at storage temperatures 4–20 \({}^{\circ}\)C. Lines represent the prediction of the shelf life based on the overall mathematical models developed. The continuous red line represents the expected shelf life of the product if untreated tomatoes had been used in the formulation.