## 3 Results and Discussion
### Instrumental Colour Measurement
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Storage Day/Variable**} & \multicolumn{4}{c}{**Treatment**} \\ \cline{2-5}  & **HF0** & **HF4** & **HF6** & **Significance** \\ \hline \hline \multicolumn{5}{c}{Raw minced meat products} \\ \hline \hline \multicolumn{5}{c}{Lightness (L*)} \\ \hline
1 & 49.30 \(\pm\)1.04 & 48.61 \(\pm\) 1.05 & 49.32 \(\pm\) 0.93 & NS \\
2 & 49.41 \(\pm\) 1.17 & 49.49 \(\pm\) 1.47 & 49.24 \(\pm\) 1.07 & NS \\
3 & 50.52 \(\pm\) 1.41 & 49.52 \(\pm\) 1.57 & 51.70 \(\pm\) 1.64 & NS \\ \hline \multicolumn{5}{c}{Redness (a*)} \\ \hline
1 & 13.40 \(\pm\) 2.05 & 14.57 \(\pm\) 1.92 & 13.75 \(\pm\) 2.35 & NS \\
2 & 13.23 b \(\pm\) 0.62 & 13.43 b \(\pm\) 0.91 & 11.50 a \(\pm\) 1.04 & ** \\
3 & 12.65 b \(\pm\) 0.99 & 11.04 b \(\pm\) 0.80 & 9.29 a \(\pm\) 1.47 & *** \\ \hline \multicolumn{5}{c}{Yellowness (b*)} \\ \hline
1 & 6.13 \(\pm\) 0.70 & 5.83 \(\pm\) 0.61 & 5.52 \(\pm\) 0.78 & NS \\
2 & 5.58 \(\pm\) 0.61 & 6.23 \(\pm\) 0.73 & 6.03 \(\pm\) 0.74 & NS \\
3 & 6.23 \(\pm\) 0.63 & 6.47 \(\pm\) 0.58 & 6.15 \(\pm\) 0.91 & NS \\ \hline \multicolumn{5}{c}{Chroma (Saturation index)} \\ \hline
1 & 14.78 \(\pm\) 1080 & 15.70 \(\pm\) 1.89 & 14.85 \(\pm\) 2.30 & NS \\
2 & 14.38 b \(\pm\) 0.51 & 14.82 b \(\pm\) 0.91 & 13.00 a \(\pm\) 1.07 & ** \\
3 & 14.11 b \(\pm\) 1.01 & 12.81 b \(\pm\) 0.72 & 11.20 a \(\pm\) 1.20 & *** \\ \hline \multicolumn{5}{c}{Hue angle} \\ \hline
1 & 24.94 \(\pm\) 4.63 & 21.98 \(\pm\) 2.65 & 22.16 \(\pm\) 3.75 & NS \\
2 & 22.92 a \(\pm\) 2.83 & 24.93 \(\pm\) 2.89 & 27.70 b \(\pm\) 3.20 & * \\
3 & 26.25 a \(\pm\) 2.43 & 30.43 \(\pm\) 3.07 & 33.82 b \(\pm\) 6.06 & * \\ \hline \multicolumn{5}{c}{Cooked minced meat products—Display day 2} \\ \hline Lightness (L*) & 32.49 \(\pm\) 6.01 & 40.46 \(\pm\) 6.02 & 42.59 \(\pm\) 8.42 & NS \\ Redness (a*) & 23.64 b \(\pm\) 8.07 & 12.14 a \(\pm\) 1.12 & 16.15 a \(\pm\) 0.85 & ** \\ Yellowness (b*) & 11.20 \(\pm\) 2.53 & 8.42 \(\pm\) 2.65 & 10.72 \(\pm\) 3.84 & NS \\ Chroma (Saturation index) & 26.20 b \(\pm\) 8.32 & 14.89 a \(\pm\) 2.04 & 19.58 b \(\pm\) 2.47 & ** \\ Hue angle & 26.37 \(\pm\) 4.18 & 34.04 \(\pm\) 7.83 & 32.73 \(\pm\) 8.86 & NS \\ \hline NS = Non-significant; * = \(p<\) 0.05; ** = \(p<\) 0.01; ** = \(p<\) 0.001; Superscripts a and b differ at \(p<\)0.05. Since there were no significant (\(p>0.05\)) differences between samples from the HF0 and HF4 treatments in terms of redness (a*) values, it can be hypothesised that there was a synergistic effect between the polyphenols present in the hemp flour and the sodium nitrate that resulted in reduced myoglobin oxidation in the samples from the HF4 and HF6 groups. Furthermore, the greater content of hemp flour in the samples from the HF6 treatment resulted in the darkening of the samples and subsequently lower redness (a*) values. The synergistic effect of polyphenols and sodium nitrites has been proposed by other researchers examining plant-based ingredients, i.e., regarding the effect of grape pomace or tea polyphenols on the colour stability of meat products [71; 72]. According to [PERSON] et al. [73], total colour difference (\(\Delta E_{\text{Lab}}\)) serves as an index for evaluating differences between samples from different treatment groups. A higher \(\Delta E_{\text{Lab}}\) value indicates greater colour difference compared to control samples. In the present study, the \(\Delta E_{\text{Lab}}\) value ranged between 2 and 3.5 for the samples from the HF0 and HF4 treatments, indicating that the colour difference was noticeable even to an inexperienced observer throughout the entire display period (Figure 2). Similarly, for the samples used in the HF0 and HF6 treatments, the \(\Delta E_{\text{Lab}}\) value ranged between 2 and 3.5 on display days 1 and 2, while it exceeded 3.5 on display day 3, indicating a clear difference [19]. However, \(\Delta E_{\text{Lab}}\) threshold values depend on the characteristics of a sample, and there are no precise data on colour difference threshold values for meat products [74].