# Comprehensive Evaluation of the Nutritional Quality of Stored Watermelon Seed Oils
## 3 Results and Discussion
### Fatty Acid Distribution  
In the composition of vegetable fats, there are, on average, 5 to 15 fatty acids. Their acid residues can occupy external (_sn_-1,3) or internal (_sn_-2) positions in TAG molecules. Under the influence of the action of a regiospecific enzyme, e.g., pancreatic lipase, it is possible to determine the FA content in these positions. The external positions of pancreatic lipase cannot be distinguished; therefore, they are assumed to be equivalent. If the FA share at _sn_-2 is below 33%, its distribution is mainly in the external TAG positions [30,38]. Table 2 shows the FA composition of the outer and inner TAG positions of the tested watermelon seed oils and Figure 1 presents the contents of the main FA share in the _sn_-2 position of TAGs. Watermelon seed oils contained the most linoleic acid in the internal position (from 39% for WO\({}_{3}\) to \(\sim\)62% for WO\({}_{\rm ext}\)), but the share of linoleic acid in the _sn_-2 position of TAGs was less than 33%. The second most abundant FA in the internal position was oleic acid (from \(\sim\)19% for WO\({}_{\rm ext}\) to \(\sim\)32% for WO\({}_{\rm ref}\)), and its share in the _sn_-2 position of TAGs was above 33.3% for all tested oils. SFAs were present in the lowest amount in the _sn_-2 position and their share in the internal position of TAGs varied depending on the type of oil used; it was more than 33.3% for WO\({}_{1}\) and WO\({}_{\rm ref}\) and less than 33.3% for WO\({}_{\rm ext}\). The share of palmitic acid in the _sn_-2 position was around 30% for WO\({}_{2}\) and \(\sim\)42% for WO\({}_{3}\), in comparison to that of stearic acid, which was \(\sim\)40 and \(\sim\)25% for these oils, respectively. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Fatty**} & \multicolumn{6}{c}{**Composition [\%]**} \\ \cline{2-7}  & & **WO\({}_{1}\)** & **WO\({}_{2}\)** & **WO\({}_{3}\)** & **WO\({}_{\rm ref}\)** & **WO\({}_{\rm ext}\)** \\ \hline \multirow{4}{*}{C16\(\circ\)0} & TAG & 11.79 \(\pm\) 0.04 b  & 11.43 \(\pm\) 0.04 b  & 12.45 \(\pm\) 0.04 b  & 12.18 \(\pm\) 0.04 b  & 11.00 \(\pm\) 0.04 b  \\ \cline{2-7}  & _sn_-2 & 12.18 \(\pm\) 0.66 ab  & 10.34 \(\pm\) 0.66 ab  & 15.68 \(\pm\) 0.66 ab  & 12.68 \(\pm\) 0.66 ab  & 9.65 \(\pm\) 0.66 ab  \\ \cline{2-7}  & _sn_-1,3 & 11.60 \(\pm\) 0.33 b  & 11.98 \(\pm\) 0.33 b  & 10.84 \(\pm\) 0.33 b  & 11.93 \(\pm\) 0.33 b  & 9.35 \(\pm\) 0.33 b  \\ \hline \multirow{4}{*}{C18\(\circ\)0} & TAG & 4.42 \(\pm\) 0.01 bc  & 4.97 \(\pm\) 0.01 bc  & 12.52 \(\pm\) 0.01 bc  & 4.85 \(\pm\) 0.01 bc  \\ \cline{2-7}  & _sn_-2 & 5.70 \(\pm\) 0.13 a  & 5.95 \(\pm\) 0.13 a  & 9.19 \(\pm\) 0.13 a  & 6.92 \(\pm\) 0.13 a  \\ \cline{2-7}  & _sn_-1,3 & 3.78 \(\pm\) 0.07 b  & 4.48 \(\pm\) 0.07 b  & 14.19 \(\pm\) 0.07 b  & 3.81 \(\pm\) 0.07 b  \\ \hline \multirow{4}{*}{C18\(\circ\)1} & TAG & 27.02 \(\pm\) 0.06 c  & 25.23 \(\pm\) 0.06 c  & 14.20 \(\pm\) 0.06 c  & 28.18 \(\pm\) 0.06 c  & 16.99 \(\pm\) 0.06 c  \\ \cline{2-7}  & _sn_-2 & 27.26 \(\pm\) 1.29 c  & 28.71 \(\pm\) 1.29 c  & 23.95 \(\pm\) 1.29 c  & 31.22 \(\pm\) 1.29 c  & 18.87 \(\pm\) 1.29 c  \\ \cline{2-7}  & _sn_-1,3 & 26.90 \(\pm\) 0.65 c  & 23.49 \(\pm\) 0.65 c  & 9.32 \(\pm\) 0.65 c  & 26.66 \(\pm\) 0.65 c  & 16.05 \(\pm\) 0.65 c  \\ \hline \multirow{4}{*}{C18\(\circ\)2} & TAG & 54.58 \(\pm\) 0.06 b  & 56.20 \(\pm\) 0.06 b  & 58.56 \(\pm\) 0.06 b  & 52.90 \(\pm\) 0.06 b  & 62.21 \(\pm\) 0.06 b  \\ \cline{2-7}  & _sn_-2 & 51.85 \(\pm\) 1.35 b  & 51.99 \(\pm\) 1.35 b  & 39.00 \(\pm\) 1.35 b  & 48.89 \(\pm\) 1.35 b  & 61.27 \(\pm\) 1.35 b  \\ \cline{2-7}  & _sn_-1,3 & 55.95 \(\pm\) 0.68 b  & 58.30 \(\pm\) 0.68 b  & 68.34 \(\pm\) 0.68 b  & 56.91 \(\pm\) 0.68 b  & 62.68 \(\pm\) 0.68 b  \\ \hline \end{tabular} 1  
\end{table} 
Table 2: Fatty acid composition of the outer (_sn_-1,3) and inner (_sn_-2) triacylglycerglycerools (TAGs) positions of the tested watermelon seed oils. Figure 1: The main fatty acid contents in the _sn_-2 position of the triacylglycerglycerools (_sn_-2 TAG) of the tested watermelon seed oils.