## 3 Results and Discussion
### Physicochemical and Microbiological Parameters
The trend of contamination of fillets spiked with 0.5% (T1) sumac was practically the same as that of the control samples, with a slight statistically insignificant (\(p>0.05\)) decrease in APC values after 24 h. [PERSON] et al. [50] studied the antimicrobial properties of sumac at 4 \({}^{\circ}\)C and found that the extract reduced bacterial growth. Also, [PERSON] et al. [51] evaluated the antimicrobial effect of this plant and concluded that the aqueous extract of sumac (_Rhus coviaria_) could be used as a natural antibacterial agent. For samples stored at low refrigeration temperatures, psychotrophic microorganisms adapted to low environmental temperature conditions can be expected to account for the majority of the total contamination. The dynamics of their changes closely followed the pattern of changes in APC values, including the existence of statistically significant differences between the values or inconclusive findings. It is possible that after 24 h of storage, the psychotrophic microorganisms adapted to a more acidic environment and their growth intensity increased. There were no statistically significant differences in the number of coliform bacteria (CB) in the samples based on the concentration of sumac preparation throughout the experiment. Significant differences were found in all samples between day 0 and after 24 and 72 h of cold storage, respectively, during which time there was a statistically significant (\(p<0.05\)) increase in CB counts. \begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Storage Hours**} & \multicolumn{4}{c}{**Sumac Concentration**} \\ \cline{2-5}  & **0\% (T0)** & **0.5\% (T1)** & **1.5\% (T2)** & **2.5\% (T3)** \\ \hline \multicolumn{5}{c}{Water activity} \\ \hline
0 \({}^{*}\) & 0.979 \(\pm\) 0.002 & 0.979 \(\pm\) 0.002 & 0.979 \(\pm\) 0.002 & 0.979 \(\pm\) 0.002 \\
24 & 0.974 \(\pm\) 0.005 & 0.977 \(\pm\) 0.004 & 0.975 \(\pm\) 0.003 & 0.978 \(\pm\) 0.003 \\
72 & 0.971 \(\pm\) 0.007 & 0.976 \(\pm\) 0.004 & 0.978 \(\pm\) 0.004 & 0.976 \(\pm\) 0.005 \\ \hline \multicolumn{5}{c}{pH value} \\ \hline
0 \({}^{*}\) & 6.41 \(\pm\) 0.11 \({}^{\text{A}}\) & 6.41 \(\pm\) 0.11 \({}^{\text{A}}\) & 6.41 \(\pm\) 0.11 \({}^{\text{A}}\) & 6.41 \(\pm\) 0.11 \({}^{\text{A}}\) \\
24 & 6.30 \(\pm\) 0.09 \({}^{\text{aAB}}\) & 6.21 \(\pm\) 0.21 \({}^{\text{ba}}\) & 5.90 \(\pm\) 0.20 \({}^{\text{cbB}}\) & 5.61 \(\pm\) 0.18 \({}^{\text{cB}}\) \\
72 & 6.19 \(\pm\) 0.10 \({}^{\text{aB}}\) & 6.35 \(\pm\) 0.17 \({}^{\text{a}}\) & 6.04 \(\pm\) 0.39 \({}^{\text{aABAB}}\) & 5.53 \(\pm\) 0.40 \({}^{\text{bB}}\) \\ \hline \multicolumn{5}{c}{Aerobic plate count (log CFU\(\cdot\)g\({}^{-1}\))} \\ \hline
0 \({}^{*}\) & 5.50 \(\pm\) 0.17 & 5.50 \(\pm\) 0.17 \({}^{\text{A}}\) & 5.50 \(\pm\) 0.17 \({}^{\text{A}}\) & 5.50 \(\pm\) 0.17 \({}^{\text{A}}\) \\
24 & 5.48 \(\pm\) 0.16 \({}^{\text{a}}\) & 5.32 \(\pm\) 0.04 \({}^{\text{a}}\) & 5.09 \(\pm\) 0.10 \({}^{\text{bB}}\) & 5.09 \(\pm\) 0.08 \({}^{\text{bB}}\) \\
72 & 5.55 \(\pm\) 0.13 & 5.45 \(\pm\) 0.20 & 5.33 \(\pm\) 0.16 \({}^{\text{A}}\) & 5.64 \(\pm\) 0.50 \({}^{\text{A}}\) \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Water activity, pH value and microorganism count (mean \(\pm\) SD) of raw carp fillets with sumac treatment during chilled storage.