# Optimization of HS-SPME-GC-MS for the Determination of Volatile Flavor Compounds in Ningxiang Park
## 3 Results and Discussion
### Orthogonal Test Optimized Condition Screening  
In accordance with the findings of the single-factor test, an orthogonal test was conducted to improve the HS-SPEM-GC-MS test conditions for the detection of VFCs in Ningxiang pork, and the impact of various factors on the identification of VFCs in Ningxiang pork was also discussed. In range analysis, the higher the R value is, as shown in Table 4, the greater the overall impact of this factor, offering recommendations on the level of factor to be used. The total ion chromatographic peaks of the HS-SPEM-GC-MS were considerably affected by the extraction temperature in terms of peak area. The largest impact derived the identification of the total amount of VFCs in Ningxiang pigs. The types of VFCs, particularly alcohols and aldehydes, are mostly influenced by extraction time, while the equilibrium temperature primarily affects ketones. According to the variance analysis, there was no discernible difference between the various test levels for the orthogonal test components (\(p>0.05\)). Therefore, we simply took into account the test efficiency and the actual test material content while choosing the combination of test conditions.  
The best test settings were chosen to produce a high-test efficiency, greater quantity, and higher concentration of the compounds detected: 5 g of meat samples were weighed, homogenized for 30 s in a homogenizer, heated for 30 min at 100 \({}^{\circ}\)C, equilibrated for 30 min at 70 \({}^{\circ}\)C, and extracted for 50 min at 100 \({}^{\circ}\)C.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline  & **Test Level** & \begin{tabular}{c} **Heat Treatment** \\ **Time** \\ \end{tabular} & \begin{tabular}{c} **Equilibrium** \\ **Time** \\ \end{tabular} & \begin{tabular}{c} **Equilibrium** \\ **Temperature** \\ \end{tabular} & \
\begin{tabular}{c} **Extraction** \\ **Time** \\ \end{tabular} &
\begin{tabular}{c} **Extraction** \\ **Temperature** \\ \end{tabular} \\ \hline \multirow{4}{*}{Total amount of substances} & K1 & 76.83 & 75.25 & 77.18 & 72.92 & 73.58 \\  & K2 & 73.73 & 79.5 & 78.83 & 82.82 & 77.58 \\  & K3 & 77.75 & 75.18 & 74.08 & 74.83 & 79.09 \\  & R & 4.02 & 4.32 & 4.75 & 9.90 & 5.51 \\  & K1 & \(3.74\times 10^{7}\) & \(3.85\times 10^{7}\) & \(4.10\times 10^{7}\) & \(3.36\times 10^{7}\) & \(3.41\times 10^{7}\) \\  & K2 & \(3.74\times 10^{7}\) & \(3.79\times 10^{7}\) & \(3.65\times 10^{7}\) & \(4.21\times 10^{7}\) & \(3.57\times 10^{7}\) \\  & K3 & \(4.01\times 10^{7}\) & \(3.99\times 10^{7}\) & \(3.89\times 10^{7}\) & \(4.07\times 10^{7}\) & \(4.70\times 10^{7}\) \\  & R & \(2.72\times 10^{7}\) & \(1.93\times 10^{7}\) & \(4.4\times 10^{7}\) & \(8.54\times 10^{6}\) & \(1.29\times 10^{7}\) \\  & K1 & 13.17 & 13.67 & 13.73 & 13.25 & 14.42 \\ Alcohols’ & K2 & 13.45 & 13.75 & 13.58 & 15.73 & 13.33 \\ number & K3 & 14.50 & 14.00 & 14.08 & 12.58 & 13.64 \\  & R & 1.33 & 0.33 & 0.50 & 3.14 & 1.08 \\  & K1 & 3.00 & 3.67 & 2.91 & 3.42 & 4.08 \\ Ketones’ & K2 & 4.09 & 3.58 & 4.42 & 4.55 & 4 \\ number & K3 & 4.25 & 4.36 & 4.17 & 3.67 & 3.45 \\  & R & 1.25 & 0.78 & 1.51 & 1.13 & 0.63 \\  & K1 & 29.08 & 30.33 & 29.64 & 28.67 & 28.92 \\ Aldehydes’ & K2 & 28.18 & 28.5 & 29.58 & 30.55 & 29.58 \\ number & K3 & 29.17 & 28.73 & 28.42 & 28.50 & 29.09 \\  & R & 0.98 & 1.83 & 1.22 & 2.05 & 0.67 \\  & K1 & \(2.564\times 10^{7}\) & \(2.606\times 10^{7}\) & \(2.803\times 10^{7}\) & \(2.235\times 10^{7}\) & \(2.170\times 10^{7}\) \\ Aldehyde total & K2 & \(2.544\times 10^{7}\) & \(2.582\times 10^{7}\) & \(2.407\times 10^{7}\) & \(2.821\times 10^{7}\) & \(2.408\times 10^{7}\) \\ peak area & K3 & \(2.645\times 10^{7}\) & \(2.679\times 10^{7}\) & \(2.668\times 10^{7}\) & \(2.823\times 10^{7}\) & \(3.344\times 10^{7}\) \\  & R & \(1.007\times 10^{6}\) & \(9.721\times 10^{5}\) & \(3.964\times 10^{6}\) & \(5.887\times 10^{6}\) & \(1.173\times 10^{7}\) \\ \hline \hline \end{tabular}
\end{table}
Table 4: HS-SPEM-GC-MS range analysis.