## 3 Results and Discussion
### Nitrates and Nitrites Content  
The dynamics of nitrates and nitrites transformation in meat products during storage depends on many parameters including environment acidity, redox potential, and the amount of reducing substances [44]. In both experimental sausages a statistically significant (_p_ < 0.05) reduction of nitrites level during storage was observed. No differences (_p_ > 0.05) in NO\({}_{2}\) content was observed between the treatments during cold storage (Table 3). In the research of [PERSON] et al. [45], the decrease of nitrites level was observed in cured pork sausages during 84 days of cold storage. Similar results were reported by [PERSON] et al. [46] in the case of cured pork gates after 28 days of cold storage. Nitrites reduction in batters and meat products is connected with the reaction of these compounds with muscle and fat tissue components as well as with additional substances introduced into the meat batters [47].  
The amount of nitrates in the sausages after production was similar and reached 62.2 mg/kg in the C treatment and 66.4 mg/kg in the L treatment. The amount of nitrates  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Parameter**} & \multirow{2}{*}{**Treatment**} & \multicolumn{4}{c}{**Storage Time (Weeks)**} \\ \cline{3-5}  & & **0** & **1** & **3** \\ \hline Nitrite (mg/kg) & C & 16.5 \(\pm\) 0.2 \({}^{\text{aC}}\) & 15.4 \(\pm\) 0.1 \({}^{\text{AB}}\) & 14.4 \(\pm\) 0.1 \({}^{\text{AA}}\) \\  & L & 16.8 \(\pm\) 0.2 \({}^{\text{aC}}\) & 15.7 \(\pm\) 0.1 \({}^{\text{AB}}\) & 14.4 \(\pm\) 0.3 \({}^{\text{AA}}\) \\ Nitrate (mg/kg) & C & 62.2 \(\pm\) 4.9 \({}^{\text{AB}}\) & 49.1 \(\pm\) 0.8 \({}^{\text{AA}}\) & 65.4 \(\pm\) 2.4 \({}^{\text{AB}}\) \\  & L & 66.4 \(\pm\) 3.0 \({}^{\text{AB}}\) & 49.3 \(\pm\) 1.1 \({}^{\text{AA}}\) & 67.1 \(\pm\) 0.6 \({}^{\text{AB}}\) \\ Total heme pigments content & C & 113.56 \(\pm\) 0.68 \({}^{\text{AB}}\) & 110.84 \(\pm\) 1.18 \({}^{\text{AA}}\) & 114.01 \(\pm\) 0.39 \({}^{\text{AB}}\) \\ (ppm) & L & 116.51 \(\pm\) 1.96 \({}^{\text{AB}}\) & 109.48 \(\pm\) 0.68 \({}^{\text{AA}}\) & 112.20 \(\pm\) 1.80 \({}^{\text{AA}}\) \\ NOMb content (g/100 g) & C & 75.93 \(\pm\) 1.52 \({}^{\text{BB}}\) & 78.84 \(\pm\) 1.04 \({}^{\text{AB}}\) & 58.93 \(\pm\) 2.73 \({}^{\text{AA}}\) \\  & L & 70.86 \(\pm\) 0.76 \({}^{\text{AA}}\) & 76.29 \(\pm\) 3.30 \({}^{\text{AA}}\) & 64.96 \(\pm\) 1.07 \({}^{\text{BA}}\) \\ \hline \hline \end{tabular}  
* C—control treatment with MSPM without a bacteria strain, L—treatment with MSPM and the bacteria _L. plantarum_ SCH1 (10\({}^{7}\) cfu/g). Various small letters (a–b) in the same column indicate significant differences between treatments (_p_ < 0.05). Various capital letters (A–C) in the same line indicate significant differences while being stored (_p_ < 0.05).  
\end{table}
Table 3: Nitrite and nitrate (mean \(\pm\) SD), total heme pigments (mean \(\pm\) SD) and nitrosyl myoglobin content (mean \(\pm\) SD) changes in the model sausages with MSPM during storage.  
decreased after 1 week of storage to approx. 49 mg/kg in both of the experimental sausages. Next, the significant increase of nitrates content was observed to the level of 65.4 mg/kg and 67.1 mg/kg respectively in treatment C and 7 after 3 weeks of storage (\(p<0.05\)). Nitrates reduction in the tested meat products could be performed with the participation of bacterial enzymes. Whereas the observed nitrates increase in the products was probably caused by the transformation of residual nitrites during cold storage [42]. The introduction of lactic acid bacteria did not have a significant effect (\(p>0.05\)) on nitrites and nitrates level in the L treatment (Table 3).