## 3 Results and Discussion
### Effect of HP Treatment on Microbial Growth of Bratwurst Sausages  
The effect of storage temperature (0-15 \({}^{\circ}\)C) on the growth of total viable count (TVC) for all samples was studied. High Pressure processing induced a reduction of initial total microbial count up to 4.2 log CFU/g, depending on the product studied (by 4.2 log CFU/g for Ham cubes, 3.2 log CFU/g for sliced turkey, 3.8 log CFU/g for sliced ham). For Bratwurst sausages, the initial count of nitrite containing samples (4.2 log CFU/g) was less by 0.9 log CFU/g compared to nitrite-free, whereas after HP treatment, it was less by 1.7 log CFU/g than the respective of control samples. Growth rates (\(\mu_{\text{max}}\)) at different storage temperatures are presented in Table 2. HP-treated samples were spoiled slower compared to control and nitrite-free sausages. Storage at 0 \({}^{\circ}\)C resulted in growth rates of total aerobic count of approximately 0.040, 0.092, and 0.197 days\({}^{-1}\) for HP treated, with nitrites and control samples, respectively. After 80 days storage at 0 \({}^{\circ}\)C, total microbial count of HP-treated samples was lower than 6 log CFU/g, while nitrite containing and control samples reached 6 log CFU/g at 25 and 10 days, respectively (Figure 1). HP treatment in combination with low storage temperatures provided a significant (\(p\) < 0.05) inhibition of total aerobic count. The effect of storage temperature on the growth rates of total microflora was expressed through the activation energy (E\({}_{\text{a}}\)) value, estimated as 69, 94, and 123 kJ/mol for control, nitrite containing, and HP treated samples, respectively. Higher E\({}_{\text{a}}\) values denote higher dependence of the growth rate to storage temperature increase. Thus, at 10 \({}^{\circ}\)C, the growth rate increase by 2.4, 4.3, and 9.1 times, respectively, compared to growth rates at 0 \({}^{\circ}\)C. However, the growth in the HP treated samples is still the lowest (0.364 compared to 0.474 and 0.403 for the control and nitrite containing samples, respectively). Lactic acid bacteria (LAB) are the predominant spoilage microflora in meat products under vacuum and at refrigeration conditions [25; 26], while at those conditions, _Pseudomonas_ are significantly inhibited [27]. During the whole storage period studied, \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{3}{*}{**Process Conditions**} & \multicolumn{3}{c}{**Sliced Cooked Ham**} & \multicolumn{3}{c}{**Sliced Cooked Turkey**} & \multicolumn{3}{c}{**Bratwurst Sausages**} \\ \cline{2-7}  & \multicolumn{3}{c}{**Total Viable**} & \multicolumn{3}{c}{**Total Viable**} & \multicolumn{3}{c}{**Total Viable**} & \multicolumn{3}{c}{**Total Viable**} \\  & **Organoleptic Scoring** & **Count at 0 min** & **Organoleptic Scoring** & **Count at 0 min** & **Organoleptic Scoring** & **Count at 0 min** \\  & & **(log CFU/g)** & & **(log CFU/g)** & & **(log CFU/g)** \\ \hline Untreated & 9 & 3.7 & 9 & 2.9 & 9 & 4.2 \\
400 MPa—25 \({}^{\circ}\)C—10 min & 8.5 & 3.1 & 8.5 & 2.6 & 8.5 & 3.0 \\
500 MPa—25 \({}^{\circ}\)C—5 min & 8.5 & 3.0 & 8.5 & 2.4 & 8.5 & 2.5 \\
500 MPa—25 \({}^{\circ}\)C—10 min & 7.5 & 2.2 & 7.5 & 2.0 & 7.5 & 2.1 \\
600 MPa—25 \({}^{\circ}\)C—5 min & 8.5 & N.D. & 8.5 & 1.0 & 8.5 & 1.5 \\
600 MPa—25 \({}^{\circ}\)C—10 min & 7 & N.D. & 7 & N.D. & 7 & N.D. \\
700 MPa—25 \({}^{\circ}\)C—5 min & 6.5 & N.D. & 6.5 & N.D. & 6.5 & N.D. \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Sensory evaluation and total microflora reduction (log CFU/g) of meat products treated at different combinations of pressure and time at 25 \({}^{\circ}\)C.  
_Pseudomonas_ spp. population was below the detection limit (\(<\)10\({}^{2}\) CFU/g). Growth rates of LAB for all treatments and temperature conditions are presented in Table 2. The effect of storage temperature was expressed by the E\({}_{\text{a}}\) values (Table 2). LAB are relatively resistant to sodium nitrite [28].