## 3 Results and Discussion  
### Caffeine, Chlorogenic Acid, and Trigonelline Compounds in CB Coffee Samples  
Alkaloids, such as caffeine, chlorogenic acids, and trigonelline, are crucial to the coffee flavor [1]. Bitterness was one of the main sensory attributes influencing consumer acceptability [15]. Both caffeine and chlorogenic acid contributed to the bitterness, whereas the latter was also responsible for astringency [1, 16]. \(p\)-values of caffeine, chlorogenic acid, and trigonelline contents in the CB and CM samples are listed in Table 2. The coffee variety (brand) and brewing method significantly affected these contents. The caffeine content was affected by both the coffee variety (brand) and brewing method, whereas the chlorogenic acid and trigonelline contents were significantly affected by the coffee variety. The amounts of the three non-volatile compounds are shown in Table 3. Generally, the RTD samples had the lowest amounts of these compounds. The caffeine contents descended in the following order: Those of FolgersCM, StarbucksCS, FolgersCB, and TwosomeplaceCS. The contents of chlorogenic acid and trigonelline were the highest in the StarbucksCS and FolgersCM samples. The CB and CM samples, except the Folgers samples, generally showed moderate contents: 0.74-0.8 mg/mL (caffeine), 0.18-0.23 mg/mL (chlorogenic acid), and 0.19-0.27 mg/mL (trigonelline) (Table 3). [PERSON] and \begin{table}
\begin{tabular}{c c c c} \hline \hline  & \multicolumn{3}{c}{\(p\)**-Value**} \\ \cline{2-4}  & **Variety (Brand) 1** & **Brewing Method 2** & **Variety \(\times\) Brewing Method** \\ \hline Caffeine & \textless{}0.0001 & 0.0011 & 0.0008 \\ Chlorogenic acid & \textless{}0.0001 & 0.4740 & 0.0070 \\ Trigonelline & \textless{}0.0001 & 0.4970 & 0.0094 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Effects of coffee variety (brand) and brewing method on the \(p\)-values of caffeine, chlorogenic acid, and trigonelline contents in cold brew (CB) and coffee maker (CM) samples. [PERSON] [17] studied the contents of caffeine, chlorogenic acid, and trigonelline using different extraction methods. They used Kenya AA coffee samples and steeped the coffee grounds for 9 h to obtain CB coffee. The contents of caffeine, chlorogenic acid, and trigonelline were 0.69 mg/mL, 0.26 mg/mL, and 0.41 mg/mL, respectively. Although they used 50 g of ground coffee from beans and 500 mL of water to obtain the coffee samples, the contents of non-volatile compounds (except trigonelline) were similar to those in this study. In addition, in Blending, Colombia, and Kenya coffee samples, BlendingCB and BlendingCM contained slightly lower amounts of chlorogenic acid. [PERSON] and [PERSON] [18] analyzed the caffeine and 3-chlorogenic-acid (3-CGA) contents in coffee prepared from grounds with different degrees of roasting and granule sizes and reported that the roasting temperature could affect the 3-CGA content. However, there was no significant difference between cold and hot brewed coffee [18]. Given that the blending samples underwent a stronger roasting level (city roasting) than other samples (generally medium roasting), a higher roasting temperature might influence the degradation of chlorogenic acid, leading to a reduction in its amount in the final coffee samples. The loss in caffeine content due to general roasting is very low unless the coffee bean undergoes extreme-dark roasting [3]. The caffeine contents of CM samples (Colombia, Folgers) were higher than those of the CB samples, showing that the caffeine contents in these coffee samples were influenced by the brewing method (CB and CM). Considering that the caffeine content was higher in the 22 \({}^{\circ}\)C coffee samples than in the 5 \({}^{\circ}\)C samples [13], irrespective of the extraction method (brewing and dripping), this difference in caffeine content between the CB and CM samples was considered to be due to the extraction temperature. Furthermore, grinding and brewing methods can influence the caffeine content [19].