## 3 Results and Discussion
### Principal Component Analysis  
PCA was performed using the contents of TP, TF, CGA, and caffeine, DPPH radical scavenging activity, FRAP, and TEAC as variables (Figure 1). The first two principal components (PC) described 87.43% of the cumulative percentage of the total variation in espresso. The PC1 explained 69.68% of the total variance of the results. Variables including TP, TF, CGA, FRAP, and DPPH radical scavenging activity were highly negatively correlated with the PC1, but the caffeine had a strong positive correlation with this component. The PC2 accounted for 17.74% of the total variance and mainly accounted for the TEAC. In the drip, PCA showed an overall variation of 88.72%, explained by PC1 (72.72%) and PC2 (16.00%). Like the expresso, TP, TF, CGA, FRAP, and DPPH radical scavenging activity were highly negatively correlated with the PC1, and the caffeine had a strong positive correlation with this component. In both extracts, FRAP showed a close association with the PC1 compared to other antioxidant assays such as DPPH radical scavenging activity and TEAC. The DPPH radical scavenging activity and TEAC measure the relative antioxidant power of scavenging radicals [44], while the FRAP analyzes the antioxidant activity through electron-donating ability [48]. When PCA was performed in all extracts, TP, TF, CGA, FRAP, and DPPH radical scavenging activity were located close to each other in the same direction and had a strong negative loading on PC1. CGA and caffeine strongly correlated with PC1; however, CGA had a positive loading on PC2, whereas caffeine showed a negative loading on PC2. The calculated score plots show the position of the investigated samples in a \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Variables** & **TP** & **TF** & **CGA** & **Caffeine** & **DPPH\(\bullet\)** & **FRAP** & **TEAC** \\ \hline TP & 1 & & & & & \\ TF & 0.754 ** & 1 & & & & \\ CGA & 0.955 *** & 0.838 *** & 1 & & & \\ Caffeine & \(-\)0.987 *** & \(-\)0.758 ** & \(-\)0.978 *** & 1 & & \\ DPPH\(\bullet\) & & & & & & \\ scavenging activity & 0.664 ** & 0.238 ** & 0.679 ** & \(-\)0.691 ** & 1 & \\ FRAP & 0.723 ** & 0.751 ** & 0.843 *** & \(-\)0.761 ** & 0.630 * & 1 & \\ TEAC & 0.130 ** & \(-\)0.066 ** & 0.224 ** & \(-\)0.215 ** & 0.423 ** & 0.406 ** & 1 \\ \hline \hline \end{tabular}  
* Significant correlation with \(p<0.001\); *
* Significant correlation with \(p<0.01\);
* Significant correlation with \(p<0.05\). TP, total phenolics; TE, total flavonoids; CGA, chlorogenic acids; DPPH, 2,2-diphenyl-l-picrylhydraz; FRAP, ferric reducing antioxidant power; TEAC, Trolox equivalent antioxidant capacity; ns, not significant.  
\end{table} 
Table 6: Pearson’s correlation coefficients (r) for the total phenolics, total flavonoids, chlorogenic acids, caffeine contents, and antioxidant activities in the espresso coffee. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Variables** & **TP** & **TF** & **CGA** & **Caffeine** & **DPPH\(\bullet\)** & **FRAP** & **TEAC** \\ \hline TP & 1 & & & & & \\ TF & 0.927 *** & 1 & & & & \\ CGA & 0.966 *** & 0.977 *** & 1 & & & \\ Caffeine & \(-\)0.951 *** & \(-\)0.854 *** & \(-\)0.941 *** & 1 & & \\ DPPH\(\bullet\) & & & & & & \\ scavenging activity & 0.563 * & 0.674 ** & 0.686 ** & \(-\)0.638 * & 1 & \\ FRAP & 0.878 *** & 0.915 *** & 0.885 *** & \(-\)0.777 ** & 0.454 ** & 1 & \\ TEAC & 0.198 ** & 0.169 ** & 0.116 ** & \(-\)0.001 ** & \(-\)0.156 ** & 0.124 ** & 1 \\ \hline \hline \end{tabular}  
* Significant correlation with \(p<0.001\); *
* Significant correlation with \(p<0.01\);
* Significant correlation with \(p<0.05\). TP, total phenolics; TE, total flavonoids; CGA, chlorogenic acids; DPPH, 2,2-diphenyl-l-picrylhydraz; FRAP, ferric reducing antioxidant power; TEAC, Trolox equivalent antioxidant capacity; ns, not significant.  
\end{table} 
Table 7: [PERSON]’s correlation coefficients (r) for the total phenolics, total flavonoids, chlorogenic acids, caffeine contents, and antioxidant activities in the drip coffee. multivariate space consisted of the two PCs.