## 2 Materials and Methods  
### Production of Fermented Loins  
The raw materials for the production of experimental meat products were loins (_m. longissimus thoracis et lumborum_) from Polish large white purebred fatteners at 24 h after slaughter. The loins were obtained from a slaughterhouse located near Bilgoraj (in Eastern Poland). The raw materials were delivered in hygienic and cooling conditions to the Department of Meat Technology and Food Quality of University of Life Sciences in Lublin. Then, they were stored at 4 \(\pm\) 2 \({}^{\circ}\)C during 24 h. After a day had passed, the meat was prepared for processing to obtain fermented loins. Preparation included the cleaning of the surface of the fascia, removing the protruding parts of the muscle, and giving the portion with a similar weight (2.0 \(\pm\) 0.5 kg). The loins prepared in this way were divided into parts of about 500 g. Prepared parts of meat have been processed using the following operations: (1) salting (2.8%) with sea salt or curing (2.8%) with a mixture containing sea salt (99.5%) and sodium nitrate(V) (0.5%) using a surface massage, and (2) fermentation and maturation in the fermentation chamber. The addition of glucose in the amount of 6 g kg\({}^{-1}\) was used for all samples. Four different sample groups of fermented loins were produced with various percentages of sodium nitrate (0, 50, 100, and 150 mg kg\({}^{-1}\)). Fermentation and maturation were carried out in a chamber under controlled conditions for 30 days under controlled humidity and temperature. After production, the finished products were packed in nylon-polyethylene bags ensuring vacuum conditions. The samples were stored at the temperature of 4 \(\pm\) 2 \({}^{\circ}\)C until analysis. The first analyzes were made on the next day after packing the products (zero months), the next after one, four and six months of storage. The formulation of fermented loin treatment, production and storage conditions are given in the Table 1. The production and analysis of fermented loins were replicated independently twice. For each replicate, thirty-two fermented loin samples were produced (eight per treatment). At the end of production, proximate chemical composition, pH, water activity, thiobarbituric acid reactive substances (TBARS), color parameters, N-nitrosamines content and nitrate and nitrite residues were determined, whereas samples at one, four and six months of storage were tested for pH, water activity, TBARS, color parameters, N-nitrosamines content and nitrate and nitrite residues. The cross-sectional appearance of fermented loins after the production process and after six months of storage are presented in Figure 1.  
\begin{table}
\begin{tabular}{c c c c} \hline  & **FL0** & **FL50** & **FL100** & **FL150** \\ \hline Sodium nitrate & & & & \\ (mg kg\({}^{-1}\)) & 0 & 50 & 100 & 150 \\ \hline \end{tabular}
\begin{tabular}{c c c} \hline \multicolumn{4}{c}{fermentation chambers under controlled humidity (RH) and temperature (T)} \\ \cline{2-3} Production & Stage 1 & Stage 2 & Stage 3 \\ conditions & T 20–22 \({}^{\circ}\)C & T 14–16 \({}^{\circ}\)C & T 13 \({}^{\circ}\)C \\  & RH 55–63\% & RH 68–75\% & RH 76\% \\  & 3 days & 3 days & 24 days \\ \hline Storage & & & \\ conditions & & & & \\ \hline FL0 (sample without sodium nitrate addition): FL50 (sample with reduced amount of sodium nitrate to 50 mg kg\({}^{-1}\)); FL100 (sample with reduced amount of sodium nitrate to 100 mg kg\({}^{-1}\)); FL150 (sample with traditional amount of sodium nitrate 150 mg kg\({}^{-1}\)). \\ \hline \end{tabular}
\end{table}
Table 1: Formulations of fermented loin treatment, production and storage conditions.