## 3 Results and Discussion
### Oxidation Status
\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}{Fat content (\%)} \\ \hline
0 * & 8.50 \(\pm\) 2.98 & 8.28 \(\pm\) 2.94 & 8.11 \(\pm\) 1.24 & 8.39 \(\pm\) 2.97 \\
24 & 6.97 \(\pm\) 3.04 & 7.79 \(\pm\) 2.76 & 6.11 \(\pm\) 1.71 & 8.36 \(\pm\) 2.60 \\
72 & 8.82 \(\pm\) 3.75 & 6.61 \(\pm\) 1.88 & 8.23 \(\pm\) 3.71 & 7.88 \(\pm\) 2.48 \\ \hline \multicolumn{5}{c}{TBARS (mg MDA kg\({}^{-1}\))} \\ \hline
0 * & 1.63 \(\pm\) 0.31 & 1.62 \(\pm\) 0.31 A & 1.67 \(\pm\) 0.30 A & 1.66 \(\pm\) 0.30 A \\
24 & 1.24 \(\pm\) 0.28 & 0.77 \(\pm\) 0.33 B & 0.90 \(\pm\) 0.10 B & 1.09 \(\pm\) 0.37 B \\
72 & 1.73 \(\pm\) 1.35 & 0.70 \(\pm\) 0.10 B & 0.90 \(\pm\) 0.27 B & 1.02 \(\pm\) 0.32 B \\ \hline \multicolumn{5}{c}{Antioxidant capacity (DPPH \% inhibition)} \\ \hline
0 * & 32.70 \(\pm\) 1.51 & 32.82 \(\pm\) 1.49 & 32.64 \(\pm\) 1.49 C & 32.48 \(\pm\) 1.43 B \\
24 & 31.11 \(\pm\) 2.39 C & 32.67 \(\pm\) 2.83 Cb & 34.81 \(\pm\) 1.85 Bb & 35.96 \(\pm\) 2.88 ABab \\
72 & 31.02 \(\pm\) 1.64 C & 32.95 \(\pm\) 1.04 b & 37.23 \(\pm\) 1.43 Aa & 37.93 \(\pm\) 1.69 Aa \\ \hline \multicolumn{5}{c}{TVB-N (mg N/100 g)} \\ \hline
0 * & 15.46 \(\pm\) 0.75 B & 15.45 \(\pm\) 0.80 AB & 15.48 \(\pm\) 0.79 B & 15.47 \(\pm\) 0.80 AB \\
24 & 16.95 \(\pm\) 0.73 A & 16.15 \(\pm\) 0.78 A & 16.57 \(\pm\) 1.33 A & 15.93 \(\pm\) 0.88 A \\
72 & 15.34 \(\pm\) 0.55 B & 14.75 \(\pm\) 0.38 B & 15.19 \(\pm\) 0.81 B & 15.11 \(\pm\) 0.24 B \\ \hline \multicolumn{5}{c}{Free fatty acids (\% total fat as oleic acid)} \\ \hline
0 * & 0.45 \(\pm\) 0.07 A & 0.45 \(\pm\) 0.08 A & 0.45 \(\pm\) 0.08 & 0.44 \(\pm\) 0.07 \\
24 & 0.28 \(\pm\) 0.05 Cc & 0.36 \(\pm\) 0.06 Cb & 0.42 \(\pm\) 0.08 b & 0.48 \(\pm\) 0.08 ab \\
72 & 0.37 \(\pm\) 0.08 B & 0.43 \(\pm\) 0.08 AB & 0.39 \(\pm\) 0.13 & 0.40 \(\pm\) 0.09 \\ \hline \hline \end{tabular}  
* Values in the same row are significantly (\(p<0.05\)) different between sumac concentrations; A–– values in the same column are significantly (\(p<0.05\)) different between storage hours;
* control samples (without sumac application).  
\end{table} 
Table 2: Fat content and parameters of oxidation status (mean \(\pm\) SD) of raw carp fillets with sumac treatment during chilled storage. Antioxidant capacity has been widely evaluated recently using many determination methods. DPPH (2,2-diphenyl-1-picrylhydrazyl) is a stable free radical and becomes a stable diamagnetic molecule by accepting an electron or hydrogen radical. Determination of the radical-scavenging activity of the DPPH radical is performed by reduction in absorbance at 515 nm that is induced by antioxidants. The antioxidant capacity of the investigated samples at 24 and 72 h of storage increased with sumac application (T1) and with elevation in sumac treatment ratio (T1, T2 and T3). The antioxidant capacity of T2 and T3 increased gradually during the storage period. [PERSON] et al. [30] indicated that sumac seed extract is a potential source of natural antioxidant. They found that sumac seed extract contained large amounts of phenolic and flavonoid compounds and was a good scavenger of reactive oxygen species (ROS). The strong antioxidant activity of sumac is attributed to its high content of anthocyanins and hydrolysate tannins [30]. TVB-N is generally accepted as an indicator of fish spoilage that is elevated by the effect of spoilage bacteria and endogenous enzyme activity. TVB-N includes nitrogenous compounds such as ammonia, dimethylamine (DMA), trimethylamine (TMA), and others [31]. The TVB-N of the analysed samples increased slightly within 24 h, and then a significant decrease in values was observed in all study groups. It can be hypothesised that the activity of endogenous autolytic enzyme activity in muscles was maintained at a low level during storage due to low storage temperature [32]. The protective effect of sumac was not observed in our experiment.