## 2 Results and Discussion
### Targeted Analysis of Aroma-Related Volatile Compounds
#### 2.1.1 Aroma-Related Volatiles
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Chemical Family** & **Compound** & **Aroma Description** & **CAS** \\ \hline Pyridines & Pyridine, 3-ethyl- & Rotten fish, smoky, leather, tobacco, caramel, & 536-78-7 \\  & Ethanone, 1-(2-pyridinyl)- & Poprocm, bready, tobacco, cracker-like, & 1122-62-9 \\ \hline Pyrazine, methyl- & Nutty, cocoa, green, roasted, chocolate, & 109-08-0 \\  & Pyrazine, 2,5-dimethyl- & Nutty, roasted, grassy, chocolate, earthy & 123-32-0 \\  & Pyrazine, 2,6-dimethyl- & Chocolate, cocoa, toasted nuts, roasted meat & 108-50-9 \\  & Pyrazine, ethyl- & Earthy, musty, peanut butter, nutty, woody, & 13925-00-3 \\  & Pyrazine, 2,3-dimethyl- & Nutty, roasted, green, sweet & 5910-89-4 \\ Pyrazines & Pyrazine, 2-ethyl-6-methyl- & Earthy, musty, mold, floweringy, fruits, & 13925-03-6 \\  & Pyrazine, 2-ethyl-5-methyl- & hazelnut-like, toasted & 13925-03-6 \\  & Pyrazine, 2-ethyl-5-methyl- & Onion, garlic, sulfurous & 13360-64-0 \\  & Pyrazine, ethenyl- & Nutty, green, burnt & 4177-16-6 \\  & Pyrazine, 3-ethyl-2,5-dimethyl- & Earthy, moldy, roasted & 13360-65-1 \\  & Pyrazine, 2-ethenyl-6-methyl- & Coffee & 13925-09-2 \\  & Pyrazine, 2,3-diethyl-5-methyl- & Nutty roast & 18138-04-0 \\  & Pyrazine, 2-ethenyl-5-methyl- & Coffee, beany, nutty, grassy, roasted & 13925-08-1 \\  & 1-(6-Methyl-2-pyrazinyl)-ethanoneone & Popcorn, roasted, nutty, musty, bread, crust, & 22047-26-3 \\ \hline Pyrroles & 1H-Pyrrole, 1-methyl- & Smoky, woody, herbal, sweet, animal, coffee & 96-54-8 \\  & Ethanone, 1-(1H-pyrrol-2-yl)- & Nutty, bread, walnut, licorice, cracker, & 1072-83-9 \\  & 1H-Pyrrole-2-carboxaldehyde & Musty, beefy, coffee & 1003-29-8 \\ \hline Sulfur-containing & Methanethiol & Freshness, sulfurous, fresh coffee & 74-93-1 \\ compounds & 3-Mercapto-3-methylbutanol & Smoke roast, soup-like, cooked meat, spicy, meat, chicken brothy & 34300-94-2 \\ \hline \hline \end{tabular} \({}^{1}\) It is also a sulfur-containing compound.  
\end{table} 
Table 2: The targeted aroma-related volatile compound list. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Group** & **Sample** & **Bean Species** & **Bean Origin** & **Decaffeination Process 1** \\ \hline Regular & R-R & Arabica & Latin America/India/Eastern & - \\  & & Africa & - \\ Decaf & D-R & Arabica & Latin America/India/Eastern & LiCO\({}_{2}\)/water 2 \\  & & Africa & - \\ Regular & R-F & Arabica & Latin America & - \\ Decaf & D-F & Arabica & Latin America & LiCO\({}_{2}\)/water \\ Regular & R-VO & Arabica & Brazil/Colombia & - \\ Decaf & D-VO & Arabica & Brazil/Colombia & LiCO\({}_{2}\)/water \\ Regular & R-VI & Arabica & Ethiopia/Mexico & - \\ Decaf & D-VI & Arabica & Colombia/Ethiopia & LiCO\({}_{2}\)/water \\ Regular & R-S & Arabica & - \\ Decaf & D-S & Arabica & Unknown \\ Regular & R-DE & Arabica, Robusta & - \\ Decaf & D-DE & Arabica, Robusta & DCM/water 3 \\ Regular & R-I & Arabica & - \\ Decaf & D-I & Arabica & LiCO\({}_{2}\) \\ Regular & R-L & Arabica & - \\ Decaf & D-L & Arabica & - \\ Decaf & D-L & Arabica, Robusta & scCO\({}_{2}\) \\ \hline \hline \end{tabular}  
\({}^{1}\) The decaffeination process mentioned by the vendors; 2\({}^{2}\) LiCO\({}_{2}\)/water indicate the vendor applied either LiCO\({}_{2}\) or water-based decaffeination process; 3 DCM/water indicate the vendor applied either DCM or water-based decaffeination process.  
\end{table} 
Table 3: Coffee sample list.