## 3 Results and Discussion  
### Physicochemical Properties of Canola Oil with Regard to Its Composition  
Over 90% of canola oil composition are unsaturated fatty acids, namely the oleic, linoleic and alpha-linolenic ones. Apart from the unsaturated acids there are also the saturated ones such as palmitic and stearic ones. In canola oil the small amounts of trans fat and erucic acid can be also found (Table 1). The molecules of the unsaturated and saturated fatty acids like the molecules of surfactants can be divided into two parts-hydrophobic and hydrophilic ones. The hydrophobic part is a hydrocarbon chain in which, in the case of unsaturated fatty acids, there are one or more double bonds between the carbon atoms. These bonds can make a minor contribution to the polar intermolecular interactions. The -COOH group is the hydrophilic part of unsaturated and saturated fatty acid molecules. According to [PERSON] and [PERSON] [28] the surface tension of fatty acids should depend on the orientation of their molecules towards the air phase. If the molecules are oriented by hydrophobic part towards the air, the surface tension results from the Lifshitz-van der Waals intermolecular interactions. In the case of the orientation of the molecules by hydrophilic part towards the air the surface tension of the given compound results from the Lifshitz-van der Waals and acid-base intermolecular interactions. As follows from our research, the surface tension of unsaturated fatty acids results from both the Lifshitz-van der Waals and acid-base intermolecular interactions and is smaller than that of canola oil (Table 1). However, the acid-base component (AB) of the unsaturated fatty acids surface tension is larger than that of canola oil (Table 1). It should be mentioned that the Lifshitz-van der Waals component (LW) of the oleic acid is only slightly larger than the surface tension of paraffin [26], but for the alpha-linolenic acid it is the same as that of paraffin. In the case of the linoleic acid the LW component of its surface tension is close to that of n-octane [26]. The LW component of the canola oil surface tension is close to the surface tension of polyethylene [31]. Comparing the surface tension of canola oil with that of unsaturated fatty acids and the LW and AB components of this tension raise the question why the surface tension of canola oil and its LW component is larger than the surface tension of unsaturated fatty acids and its LW component. The contribution of the Lifshitz-van der Waals and acid-base intermolecular interactions to the surface tension of unsaturated fatty acids may suggest that their molecules are oriented parallel towards the acid-air interface. In the case of canola oil, the hydrophilic group of acid molecules is probably oriented towards the oil phase with the parallel orientation of hydrophobic parts of the acid molecules at the acid-air interface. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Substance**} & \multirow{2}{*}{\%} & \(\gamma_{LV}\) & \(\gamma_{LV}^{LW}\) & \(\gamma_{LV}^{AB}\) & \(\rho\) & \(\eta\) \\  & & **[mN/m]** & **[mN/m]** & **[mN/m]** & **[g/cm\({}^{3}\)]** & **[mPa-s]** \\ \hline \hline Oleic acid & 62 & 32.00 & 26.56 & 5.44 & 0.895 & 26.91 \\ Linoleic acid & 20 & 26.09 & 22.15 & 3.94 & 0.9012 & 27.20 \\ Alpha-linolenic acid & 12 & 30.15 & 25.65 & 4.50 & 0.9134 & 27.65 \\ Palmitic acid & 3 & 29.25 & 26.25 & 2.00 & 0.9052 & 7.60 at 70 \({}^{\circ}\)C \\ Stearic acid & 2 & 29.01 & 26.51 & 2.50 & 0.842 & 9.81 at 70 \({}^{\circ}\)C \\ Trans fat a  & 0.5 & 27.51 & 25.00 & 2.51 & 0.8521 & 9.12 at 75 \({}^{\circ}\)C \\ Erucic acid & \textless{}0.1 & 28.12 & 26.12 & 2.00 & 0.8571 & 8.75 at 70 \({}^{\circ}\)C \\ n-heksane & & 18.52 & 18.52 & 0.00 & 0.6601 & 0.3102 \\ Ethanol & & 23.25 & 21.45 & 1.80 & 0.7892 & 1.22 \\ Canola oil & & 33.98 & 32.51 & 1.47 & 0.9161 & 70.45 \\ \hline \hline \end{tabular}
\end{table}