## 3 Results and Discussion
### Correlation between Phenolic Compounds and Antioxidant Potential  
To investigate the correlation between the content of phenolic compounds (TPC, TFC, and TCT) and the related antioxidant activities in the sample (DPPH, FRAP, ABTS\({}^{\bullet}\), \({}^{\bullet}\)OH-RSA, FICA, TAC), the pairwise [PERSON]'s correlation test was implemented, and the results were shown in Table 2. An absolute value of a correlation coefficient closer to 1 indicates that a stronger correlation exists. TPC and TFC were positively correlated to most antioxidant assays except FICA, indicating that the phenolic and flavonoid compounds in the coffee beans were primarily responsible for the antioxidant capacity that the sample presented [41]. TCT assay was negatively correlated with DPPH and FRAP, while it could result from the complex processing methods used in coffee bean commercial processing. The condensed tannins could be degraded into flavonoids and other simple phenolics during the fermentation and roasting processing, resulting in improved TFC and TPC values. LS-ESI-QTOF-MS/MS Characterization of Phenolic Compounds in Roasted Fermented and Unfermented Coffee Beans  
The phenolic compounds present in both fermented and unfermented coffee beans, including phenolic acids, lignans, stilbenes, flavonoids, isoflavoids, and other polyphenols, were analyzed in an untargeted manner and were tentatively identified and characterized based on their \(m/z\) values and MS spectra, using both negative and positive modes of ionization. The compounds selected for further analysis and verification underwent MS/MS analysis and were chosen based on criteria such as a mass error of less than 5 ppm and a score higher than 80 in the PCDL library. The two Edward's Venn diagrams in Figure 1 were generated based on the phenolic compound profiles that were identified in the fermented and unfermented coffee beans. A total of 131 phenolic compounds were identified based on the LC-ESI-QTOF-MS/MS method in this study, and there were 24 phenolic compounds identified in both fermented and unfermented coffee beans. As shown in Figure 1, the fermented coffee beans contain more unique (\(n=86\)) and total phenolic compounds (\(n=110\)) than the unfermented coffee beans (\(n=21\)). Fermented Geisha has the largest phenolic profiles (\(n=73\)) identified among the other group of coffee beans, followed by fermented Bourbon coffee beans (\(n=65\)), sharing 18 compounds in total and 17 compounds identified only in the fermented coffee beans. One phenolic compound (Dihydromyricetin 3-O-rhammoside) was identified in all coffee samples. These Edward's Venn graphs also demonstrate that fermentation has the potential to enhance the production of a variety of phenolic compounds via the degradation of free phenolic compounds and the release of bound phenolic compounds, which are consistent with the TPC results [42]. As observed in Table 3, 18 phenolic compounds were identified and characterized in the fermented and unfermented coffee samples, in which 3 were Hydroxycinnamic acids, 4 were lignans, 1 stilbene, 3 flavonoids, 1 flavone, 1 anthocyanin, 2 hydroxycounarins, and 1 furanocumarin. \begin{table}
\begin{tabular}{l l l l l l l l l l l l} \hline  & TPC & TFC & TCT & DPPH & FRAP & ABTS-+ & -OH & FICA & RPA & TAC \\ \hline TPC & 1 & & & & & & & & & & \\ TTC & 0.997 * & 1 & & & & & & & & & \\ TCT & 0.918 * & 0.900 * & 1 & & & & & & & & \\ DPPH & 0.859 * & 0.873 * & 0.605 & 1 & & & & & & & \\ FRAP & 0.918 * & 0.935 * & 0.702 & 0.966 * & 1 & & & & & & \\ ABTS-+ & 0.917 * & 0.900 * & 0.808 & 0.876 * & 0.837 * & 1 & & & & & \\ -OH & 0.986 * & 0.979 * & 0.904 * & 0.856 * & 0.905 * & 0.919 * & 1 & & & \\ FICA & \(-\)0.357 & \(-\)0.348 & \(-\)0.601 & \(-\)0.061 & \(-\)0.092 & \(-\)0.290 & \(-\)0.382 & 1 & & & \\ RPA & 0.953 * & 0.942 * & 0.820 & 0.908 * & 0.909 * & 0.960 * & 0.975 * & \(-\)0.279 & 1 & & \\ TAC & 0.992 * & 0.985 * & 0.949 * & 0.824 & 0.884 * & 0.910 * & 0.985 * & \(-\)0.451 & 0.943 * & 1 \\ \hline \end{tabular}  
* Significant correlation with \(p\leq 0.05\).  
\end{table}