## 3 Results and Discussion
### Oil Colour in the CIE L\({}^{*}\), a\({}^{*}\), b\({}^{*}\) System  
A product's colour indicates its attractiveness to the consumer, who often associates it with the desired taste or smell [29]. The colour of vegetable oils is related to the presence of chlorophyll and carotenoid pigments, whose content is conditioned not only by the species of raw material used for production and its maturity, but also by the technology of extraction. These pigments are an important element due to their pro- and antioxidant activity; therefore, colour, apart from influencing consumer desirability, is also an important marker of oil quality [28]. Varied colours characterised the investigated oils. They differed significantly at \(p\leq 0.05\), and the analysis with [PERSON]'s test showed the existence of several homogeneous groups (Table 2). DO and PO were the oils with the darkest colour. They were characterised by the lowest values of the L\({}^{*}\) parameter of 58.70 and 65.45, respectively. At the same time, these oils had low values of the a\({}^{*}\) parameter (6.99 and 12.71), which means that they were characterised by a green colour. However, these values were not close to \(-100\) (the extreme value for this parameter). The high content of chlorophyll pigments is responsible for the green colour of parsley seed and dill seed oils, as shown by the determination of the chlorophylls content. [PERSON] et al. [32] highlight that the presence of chlorophylls is correlated with the L\({}^{*}\) and a\({}^{*}\) components. A lower value (\(-4.57\)) of the a\({}^{*}\) parameter was achieved by BO, which in terms of this colour component was similar to the value obtained \begin{table}
\begin{tabular}{l l l l} \hline \hline \multirow{2}{*}{**Oil Sample**} & \multicolumn{3}{c}{**Colour Components**} \\ \cline{2-4}  & **L\({}^{*}\)** & **a\({}^{*}\)** & **b\({}^{*}\)** \\ \hline CO & 73.03 \({}^{\text{d}}\)\(\pm\) 0.07 & 15.04 \({}^{\text{c}}\)\(\pm\) 0.02 & 104.06 \({}^{\text{c}}\)\(\pm\) 0.06 \\ FO & 71.67 \({}^{\text{c}}\)\(\pm\) 0.01 & 40.73 \({}^{\text{f}}\)\(\pm\) 0.01 & 122.40 \({}^{\text{e}}\)\(\pm\) 0.04 \\ BO & 96.69 \({}^{\text{g}}\)\(\pm\) 0.01 & \(-\)4.57 \({}^{\text{a}}\)\(\pm\) 0.01 & 50.79 \({}^{\text{a}}\)\(\pm\) 0.07 \\ PO & 65.45 \({}^{\text{b}}\)\(\pm\) 0.01 & 12.71 \({}^{\text{bc}}\)\(\pm\) 0.00 & 108.18 \({}^{\text{d}}\)\(\pm\) 0.07 \\ WCO & 83.29 \({}^{\text{f}}\)\(\pm\) 0.02 & 23.43 \({}^{\text{d}}\)\(\pm\) 0.00 & 137.85 \({}^{\text{f}}\)\(\pm\) 0.02 \\ DO & 58.70 \({}^{\text{a}}\)\(\pm\) 0.10 & 6.99 \({}^{\text{b}}\)\(\pm\) 0.03 & 97.59 \({}^{\text{b}}\)\(\pm\) 0.14 \\ TO & 79.09 \({}^{\text{e}}\)\(\pm\) 0.01 & 29.87 \({}^{\text{e}}\)\(\pm\) 0.01 & 131.86 \({}^{\text{g}}\)\(\pm\) 0.11 \\ \hline \hline \end{tabular} \({}^{\text{ab},c}\)–mean values denoted in columns by the same letters are not statistically significantly different at \(p\)-value \(\leq 0.05\).  
\end{table} 
Table 2: Colour components in the CIE L\({}^{*}\), a\({}^{*}\), b\({}^{*}\) system of analysed oils. by [PERSON] et al. [33] for cumin oil (a* = \(-\)4.51). However, the highest value of the L* parameter was determined in the case of BO (96.69), which means that its colour was the brightest. In addition, for this oil, the obtained value of parameter b* (corresponding to blue colour (b = \(-\)100) and yellow colour (b = 100)) was 50.79, which is relatively high. The oil from cress seeds achieved a high value of parameter L*, with the highest value of parameter b* among the tested oils, affecting the oil's intense orange colour. TO, CO, and FO were also characterised by similar high values of the L* component, amounting to 79.09, 73.03, and 71.67, respectively. Furthermore, each of the oils mentioned was characterised by a value of the b* parameter above 100. The strong orange colour of FO may result from a very high content of carotenoid pigments in the oil (153.68 mg/kg), as their presence affects the value of the b* component [32]. [PERSON] et al.