## 3 Results and Discussion
### Study of Coffee Silverskin Oil
#### 3.2.3 GC Study of Coffee Silverskin Oil  
The results obtained for the fatty acids composition of silverskin oil are reported in Table 3. A high unsaturated fatty acid content (UFA) (50.38%) was indicated, with 7.81% monounsaturated fatty acids and 42.57% polyunsaturated fatty acids. Among the unsaturated fatty acids, linoleic acid (C18:2, 32.47%) as a main acid followed by oleic acid (C18:1, 7.08%) was detected. Additionally, the obtained results showed significant amounts of gamma-linolenic acid, belonging to the n-6 family, and alpha-linolenic acid, eicosatrienoic acid and eicosapentaenoic acid of the n-3 family. Based on the obtained results, it can be stated that silverskin oil is an abundant source of PUFAs. Among the saturated fatty acids, the predominant fatty acid was palmitic acid, which accounted for 28.26% of fatty acids. Next to palmitic acid, high stearic acid (8.04%) and arachidonic acid (7.41%) contents were present in the triacylglycerl glycerol structure of silverskin oil. A typical chromatogram of fatty acids' composition in the tested coffee silverskin fat is shown in Figure 6.  
\begin{table}
\begin{tabular}{c c c} \hline
**Parameter** & **Value Calculated for \(\text{T}_{\text{on}}\)** & **Value Calculated for \(\text{T}_{\text{max}}\)** \\ \hline \(a\) & \(-4477.9\) & \(-4620.6\) \\ \(b\) & \(11.6\) & \(10.1\) \\ \(R^{2}\) & \(0.98\) & \(0.90\) \\ \(\text{E}_{\text{a}}\) (k/mol) & \(81.52\) & \(84.12\) \\ Z & \(7.68\times 10^{9}\) & \(2.39\times 10^{8}\) \\ \hline \end{tabular}
\end{table}
Table 2: Thermokinetic parameters of oxidative process of coffee silverskin fat.  
Additionally, in the case of silverskin oil, the n-6 to n-3 fatty acids ratio was calculated. The parameter should be considered in the fat analysis as it is of high importance in the characteristics of fat from a nutritional point of view. Nowadays, the consumption of n-6 fatty acids in the diet is at a high level, which leads to an unhealthy n-6 to n-3 ratio of 20:1 or even higher, which is associated with the risk of heart disease and brain health consequences. It is worth mentioning that commonly used oils, such as sunflower, corn, soybean and cottonseed oils, contain a high amount of n-6-family fatty acids. In the present study, for silverskin oil, the n-6 to n-3 ratio value reached 4:1, which is in  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Group of Fatty Acids** & **Fatty Acid** & **Content of Individual Fatty Acid (\%) \({}^{\star}\)** \(\Sigma\) **Content of the Group (\%) \({}^{\star}\)** \\ \hline \multirow{8}{*}{SFA} & C12:0 & \(0.08\pm 0.01\) \\  & C14:0 & \(1.86\pm 0.06\) \\  & C15:0 & \(0.19\pm 0.01\) \\  & C16:0 & \(28.26\pm 0.09\) \\  & C18:0 & \(8.04\pm 0.05\) \\  & C20:0 & \(7.41\pm 0.09\) \\  & C21:0 & \(0.33\pm 0.04\) \\  & C24:0 & \(0.20\pm 0.04\) \\ \hline \multirow{8}{*}{PUFA} & C182n-6c & \(32.47\pm 0.09\) \\  & C18:3n-6 & \(1.62\pm 0.07\) \\  & C18:3n-3 & \(1.44\pm 0.04\) \\ \cline{1-1}  & C20:2 & \(0.10\pm 0.02\) \\ \cline{1-1}  & C20:3 n-3 & \(5.50\pm 0.06\) \\ \cline{1-1}  & C22:2 & \(0.23\pm 0.04\) \\ \cline{1-1}  & C20:5 n-3 & \(1.22\pm 0.02\) \\ \hline \multirow{4}{*}{MUFA} & C16:1 & \(0.10\pm 0.01\) \\ \cline{1-1}  & C18:1n-9c & \(7.08\pm 0.04\) \\ \cline{1-1}  & C20:1 c & \(0.51\pm 0.02\) \\ \cline{1-1}  & C24:1 & \(0.12\pm 0.02\) \\ \hline \multicolumn{2}{c}{\(\Sigma\) identified} & \multicolumn{2}{c}{\(96.76\pm 0.20\)} \\ \hline \multicolumn{2}{c}{\(\Sigma\) other minor unidentified} & \multicolumn{2}{c}{\(3.24\pm 0.20\)} \\ \hline \hline \end{tabular} \({}^{\star}\) Data expressed as mean \(\pm\) standard deviation.  
\end{table}
Table 3: Fatty acids composition (%) of coffee silverskin fat samples (SFA—saturated fatty acids, MUFA—monounsaturated fatty acids, PUFA—polyunsaturated fatty acids).  
agreement with recommendations and meets the trend of searching for new sources of fats which provide a beneficial balance of n-6 to n-3 fatty acids.