## 3 Results  
Using the horizontal ISO 11290-2:2017 [46] method, we did not detect any viable \(L\). _monocytogenes_ cells in any of the LM-0 bars, which was confirmed using the enzyme-linked fluorescence assay (ELFA technique), where all results were negative, corresponding to the absence of \(L\). _monocytogenes_ in 25 g of product. The standard deviations of the \(L\). _monocytogenes_ count after the inoculation of the bars for the subsequent production series tested at day 0 were 0.06, 0.04, and 0.12 log CFU/g for LM-2 bars and 0.11, 0.18, and 0.16 log CFU/g for LM-5 bars, as it is presented in Table 2. Referring to the above, since the standard deviations of the \(L\). _monocytogenes_ count for all challenge samples on day 0 were below 0.3 log CFU/g, it can be assumed that the inoculation step was adequately carried out and can form the basis for calculating growth potential [28]. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline
**Storage** & **Sample** & **Batch** & **Day 0** & **Day 3** & **Day 7** & **Day 14** & **Day 21** & **\(\Delta_{\rm series}\)** & **\(\Delta_{\rm food}\)** \\
**Temperature** & **Code** & **Number** & & & & & & & \\ \hline \multirow{6}{*}{2 \({}^{\circ}\)C} & \multirow{6}{*}{LM-2} & 1 & 2.05 \(\pm\) 0.06 & 1.24 \(\pm\) 0.34 & 1.98 \(\pm\) 0.15 & 0.96 \(\pm\) 0.31 & 0.60 \(\pm\) 0.22 & \(-\)0.07 & \multirow{6}{*}{0.36} \\  & & 2 & 2.12 \(\pm\) 0.04 & 1.85 \(\pm\) 0.19 & 2.48 \(\pm\) 0.29 & 1.27 \(\pm\) 0.17 & 0.95 \(\pm\) 0.09 & 0.36 & \multirow{6}{*}{0.36} \\  & & 3 & 2.10 \(\pm\) 0.12 & 1.64 \(\pm\) 0.23 & 2.15 \(\pm\) 0.19 & 1.45 \(\pm\) 0.13 & 0.88 \(\pm\) 0.14 & 0.05 & \\ \cline{1-1} \cline{2-10}  & & 1 & 5.06 \(\pm\) 0.11 & 3.74 \(\pm\) 0.13 & 4.48 \(\pm\) 0.13 & 2.85 \(\pm\) 0.38 & 2.78 \(\pm\) 0.14 & \(-\)0.58 & \\ \cline{1-1} \cline{2-10}  & & 2 & 5.07 \(\pm\) 0.18 & 3.78 \(\pm\) 0.17 & 4.60 \(\pm\) 0.09 & 2.60 \(\pm\) 0.43 & 2.49 \(\pm\) 0.33 & \(-\)0.47 & \(-\)0.36 \\ \cline{1-1}  & & 3 & 5.09 \(\pm\) 0.16 & 4.11 \(\pm\) 0.18 & 4.73 \(\pm\) 0.08 & 3.35 \(\pm\) 0.15 & 3.08 \(\pm\) 0.25 & \(-\)0.36 & \\ \hline \end{tabular}
\end{table} 
Table 2: \(L\). _monocytogenes_ counts, series growth potential (\(\Delta_{\rm series}\)), and food growth potential (\(\Delta_{\rm food}\)) in LM-2 and LM-5 challenge bars stored at 2, 4, and 6 \({}^{\circ}\)C (log CFU/g). Considering a value of 0.5 log CFU/g as the threshold to define a given food matrix as able to support _L. monocytogenes_ growth [28], only the challenge bars stored at 6 \({}^{\circ}\)C proved to support the _L. monocytogenes_ growth (\(\Delta\) = 0.91 log CFU/g for LM-2 bars, and \(\Delta\) = 0.64 log CFU/g for LM-5 bars) [39]. Significantly higher (\(p<0.05\)) potential growth was reported for bars contaminated with the lower-density inoculum (LM-2 bars). The most significant variation in \(\Delta_{\rm series}\) values was observed for the LM-2 bar at 2 \({}^{\circ}\)C (SD \(\pm\)0.181), while the slightest variation was for the LM-5 bar at 6 \({}^{\circ}\)C (SD \(\pm\)0.086). The _L. monocytogenes_ growth was described using the Baranyi and Roberts model; the curves were fitted based on experimental data for each challenge RTE bar at different temperatures, as shown in Figure 2. The model courses show that when the bars were stored at 2 \({}^{\circ}\)C or 4 \({}^{\circ}\)C, the _L. monocytogenes_ population decreased regardless of the inoculum density used, while it was constant or grew when the bars were stored at 6 \({}^{\circ}\)C.  
The model developed for LM-5 bars stored at 6 \({}^{\circ}\)C most accurately predicts the missing observation, reaching the highest coefficient of determination value (R\({}^{2}\) = 0.865). In contrast, the model shows the weakest fit (R\({}^{2}\) = 0.717) for LM-2 bars stored at 2 \({}^{\circ}\)C. The remaining values related to the models, i.e.