## 3 Results and Discussion
### Physicochemical Parameters  
The density and surface tension values of flaxseed oil are presented in Table 3.  
The observed values for density were between 0.938 g/cm\({}^{3}\) at 20 \({}^{\circ}\)C and 0.901 g/cm\({}^{3}\) at 80 \({}^{\circ}\)C. According to [17], the density value is 0.9319 g/cm\({}^{3}\) at 15 \({}^{\circ}\)C, while in our study, at the lowest temperature of 20 \({}^{\circ}\)C, the measured density was 0.938 g/cm\({}^{3}\). This value does not differ from the data of other authors (\(\rho\) = 0.933 kg/m\({}^{3}\)) [20]. These data indicate that as the temperature increases, the density values tend to decrease, which has also been found for other vegetable oils [29; 49; 50]. Figure 3: GC chromatogram of the individual sterol composition of flaxseed oil: a—cholesterol; b—brasiscasterol; c—campesterol; d—stigmasterol; e—\(\Delta^{7}\)-campesterol; f—\(\beta\)-sitosterol; g—\(\Delta^{5}\)-avenasterol. It is known that the physical, physicochemical, and thermodynamic properties of vegetable oils depend on various factors, such as fatty acid composition, the content of other biologically active substances, temperature, etc. [27; 28; 29]. Surface tension and viscosity are used as measures to determine the stability of a system. The smaller the surface tension compared to that of water (72.75 mN/m, 20 \({}^{\circ}\)C), the more stable the system. Surface tension in liquids is caused by unchanged intermolecular bonding and an increase in viscosity. Any solution with a higher viscosity than water has a more minor surface tension than water. As temperature increases, viscosity and surface tension decrease. The surface tension results show values between 44.124 mN/m and 31.787 mN/m at different temperatures in our study. The values published in the literature, ranging from 23.2 to 56.1 mJ/m\({}^{2}\)[51], 12.79 dyne/cm [27] and 31.5 mN/m [17], differed from those reported in our study. The data from Table 3 show that the increase in temperature leads to a decrease in the surface tension, which confirms the findings in other studies [52]. Viscosity is a measure of the resistance of liquids to their movement, moving parallel layers relative to each other, and can be considered as a measure of fluid friction. Thus, water is defined as a liquid with a low viscosity (1 mPa.s, 20 \({}^{\circ}\)C), because its layers move with little resistance during the movement of the fluid. Vegetable oils, however, have a high viscosity because of the large resistance created when the layers move. This is called dynamic viscosity. Systems with higher viscosity are considered more stable. The viscosity of various edible vegetable oils ranged from 0.041 mPa.s to 3.115 mPa.s [27]. The results of the dynamic viscosity analysis are presented in Figure 4. Viscosity decreased with an increase in temperature. The observed values were between 29.195 mPa.s at 20 \({}^{\circ}\)C and 14.913 mPa.s at 80 \({}^{\circ}\)C. A strong linear relationship between the two parameters for the temperature range between 20 \({}^{\circ}\)C and about 45 \({}^{\circ}\)C was observed. Figure 4: Temperature dependence of the dynamic viscosity of flaxseed oil. *—dynamic viscosity values. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Temperature**, \({}^{\circ}\)**C** & **Density**, **g/cm\({}^{3}\)** & **Surface Tension**, **mN/m** \\ \hline
20 & 0.938 \(\pm\) 0.008 & 44.124 \(\pm\) 0.107 \\
30 & 0.930 \(\pm\) 0.005 & 41.924 \(\pm\) 0.114 \\
40 & 0.924 \(\pm\) 0.003 & 39.886 \(\pm\) 0.173 \\
50 & 0.921 \(\pm\) 0.008 & 37.908 \(\pm\) 0.088 \\
60 & 0.914 \(\pm\) 0.004 & 36.450 \(\pm\) 0.113 \\
70 & 0.908 \(\pm\) 0.001 & 34.170 \(\pm\) 0.174 \\
80 & 0.901 \(\pm\) 0.001 & 31.787 \(\pm\) 0.095 \\ \hline \hline \end{tabular}  
*—Mean \(\pm\) SD (n = 3).  
\end{table} 
Table 3: Density and surface tension of flaxseed oil 1. According to our findings, a rise in temperature led to the creation of deviations from the linear dependence.