## 3 Results and Discussion
The obtained values of the TBARS index (Figure 1) in thermally processed and refrigerated duck burgers indicate that the lipid oxidation process in meat products with turmeric powder was significantly (\(p\leq 0.001\)) slower on the first day of storage compared to the product with the addition of paste, turmeric extract, and the control group. The highest value of the TBARS index was found in the control product (group I) without the antioxidant component. With the passage of time for refrigerated storage of meat products, the values of the TBARS index increased in all tested samples. The increase in TBARS during refrigerated storage can be attributed to increased lipid oxidation and the production of volatile metabolites in the presence of oxygen [23]. The highest (\(p\leq 0.001\)) lipid oxidative stability during the entire storage period of duck burgers was demonstrated by the addition of turmeric powder, while the greatest (\(p\leq 0.001\)) progress in fat oxidation was recorded in the control group. On the last day of the assessment, the strongest (\(p\leq 0.001\)) effect on the lipid oxidation process in meat products was caused by the addition of turmeric powder, then paste, and to a lesser extent (\(p\leq 0.001\)), by turmeric extract (Supplementary Materials). The antioxidant effect of the addition of turmeric in meat products was also demonstrated by [PERSON] et al. [16], [PERSON] et al. [17], [PERSON] et al. [18], [PERSON] et al. [20], [PERSON] et al. [21], [PERSON] et al. [22], and [PERSON] et al. [23]. Turmeric's antioxidant property in preventing peroxide developments in foods has been confirmed in studies by [PERSON] [43]. Turmeric contains curcumin, whose antioxidant mechanism accrues the unique structure that enables it to trap oxygen-free radicals, thus acting as a chain-breaking antioxidant [39]. Furthermore, the fraction III turmeric oil obtained during curcumin extractions has been reported by [PERSON] et al. [44] to indicate a significant antioxidant effect in vitro. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline  & **Group** & \multicolumn{6}{c}{**Storage Time (Day)**} \\ \hline
**Formulations** & & **1** & **6** & **12** & **18** & **\(p\) Value** \\ \hline \multirow{6}{*}{L\({}^{\star}\), lightness} & I & a 58.01 \(\pm\) 2.29 A,B & b 63.60 \(\pm\) 0.74 A & b 63.80 \(\pm\) 0.99 B & b 62.63 \(\pm\) 1.95 A & 0.0000 \\  & II & a 62.76 \(\pm\) 2.19 A & b 66.44 \(\pm\) 0.70 A,B & b 66.30 \(\pm\) 1.05 B,C & c 68.50 \(\pm\) 1.04 B & 0.0000 \\  & III & a 58.86 \(\pm\) 3.71 B & b 66.79 \(\pm\) 2.17 A,B & b 67.75 \(\pm\) 1.53 B & b 67.02 \(\pm\) 1.18 A,B & 0.0000 \\  & IV & a 60.74 \(\pm\) 3.08 AB & b 65.34 \(\pm\) 1.08 B & b 65.72 \(\pm\) 1.74 A,C & b 66.04 \(\pm\) 1.75 A & 0.0000 \\  & \(p\) value & 0.0160 & 0.0060 & 0.0105 & 0.0063 & \\ \hline \multirow{6}{*}{a\({}^{\star}\), redness} & I & a 6.58 \(\pm\) 0.44 A & b 5.62 \(\pm\) 0.39 A & c 5.39 \(\pm\) 0.38 A & d 5.38 \(\pm\) 0.77 A & 0.0000 \\  & II & a 1.68 \(\pm\) 0.49 B & a 2.11 \(\pm\) 0.43 B & b 2.68 \(\pm\) 0.45 B & c 4.83 \(\pm\) 0.30 B & 0.0000 \\  & III & 8.52 \(\pm\) 0.91 C & 9.94 \(\pm\) 1.99 C & 9.44 \(\pm\) 0.57 C & 9.14 \(\pm\) 0.83 A & 0.0980 \\  & IV & a 3.37 \(\pm\) 0.64 D & b 3.30 \(\pm\) 0.54 B,D & c 4.04 \(\pm\) 0.90 D & c 4.81 \(\pm\) 0.71 B & 0.0000 \\  & \(p\) value & 0.0000 & 0.0000 & 0.0000 & 0.0000 & \\ \hline \multirow{6}{*}{b\({}^{\star}\), yellowness} & I & 13.46 \(\pm\) 3.06 A & 13.76 \(\pm\) 0.64 A,C & 13.43 \(\pm\) 0.33 A & 14.60 \(\pm\) 0.32 A & 0.3739 \\  & II & a  b 35.74 \(\pm\) 1.56 B & c 33.27 \(\pm\) 1.27 B & a 33.25 \(\pm\) 0.80 B & b 34.83 \(\pm\) 0.57 B & 0.0008 \\ \cline{1-1}  & III & a 13.27 \(\pm\) 0.78 A & a 13.51 \(\pm\) 0.61 C & a,b 13.87 \(\pm\) 0.42 A & b 14.41 \(\pm\) 0.71 A & 0.0023 \\ \cline{1-1}  & IV & a 34.17 \(\pm\) 1.97 B & c 32.09 \(\pm\) 1.08 D & b 3c 30.37 \(\pm\) 1.68 C & b 28.83 \(\pm\) 0.93 C & 0.0000 \\ \cline{1-1}  & \(p\) value & 0.0000 & 0.0000 & 0.0000 & 0.0000 & \\ \hline \hline \end{tabular}
\end{table}