# Quantitative Analysis of Caffe in Roasted Coffee: A Comparison of Brewing Methods
## 3 Results and Discussion
### Brewing Methods
#### 3.3.4 AeroPress  
The AeroPress method uses a device consisting of two cylinders--a smaller cylinder (equipped with an airtight seal placed inside), a larger cylinder, a piston, and a filter. Operates based on the principle of a syringe, utilizing manually generated pressure [78]. This method combines immersion and filtration techniques [77]. Coffee prepared using this method is characterized by high acidity, polyphenol content, and antioxidant potential [79]. Table 8 shows the range of caffeine content in coffee prepared using the AeroPress method, it ranged from 46.00 to 158.73 mg/100 mL. The brewing times were varied, with an average of 2 min.  
The study by [PERSON] et al. [51] used the longest extraction time among the studies analyzed and reported the highest caffeine content in the resulting brew. Similarly, the study by [PERSON] et al. [30] used a longer brewing time than [PERSON] et al. [44], with the same other parameters, and obtained a higher caffeine content. These studies confirm that a longer brewing time may favor higher caffeine extraction. This observation is consistent with theoretical predictions regarding extraction kinetics, where increased contact time  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline  & \multicolumn{3}{c}{**Brewing Parameters**} & \multicolumn{3}{c}{**Caffeine**} & \multirow{2}{*}{\begin{tabular}{c} **Caffeine** \\ **Determination** \\ **Method** \\ \end{tabular} } & \multirow{2}{*}{\
\begin{tabular}{c} **Caffeine** \\ **Content** \\ \end{tabular} } & \multirow{2}{*}{
\begin{tabular}{c} **Reference** \\ **Content** \\ \end{tabular} } \\
**Time [min]** & & & & & & & \\ \hline \hline \multicolumn{8}{c}{[mg/100 mL]} \\ \hline
5.00 & 93 & 250 & 15 & 6:100 & HPLC & 52.00 & [30] \\ \hline
5.00 & 95 & 250 & 25 & 10:100 & HPLC & 109.40 & [31] \\ \hline
5.00 & 90 & 330 & 31.5 & 9:100 & HPLC & 82.87–85.24 & [36] \\ \hline
5.00 & 90 & 250 & 22.5 & 9:100 & HPLC & 82.00 & [37] \\ \hline
6.00 & 98 & 350 & 35 & 10:100 & HPLC & 104.00–106.00 & [39] \\ \hline
8.00 & 93 & 250 & 15 & 6:100 & HPLC & 55.40–77.0 & [44] \\ \hline
4.00 & 93 & 300 & 20 & 7:100 & HPLC & 99.28–148.52 & [51] \\ \hline
4.00 & 93 & 300 & 20 & 7:100 & UHPLC & 52.66–73.47 & [52] \\ \hline \multicolumn{8}{c}{[mg/100 g]} \\ \hline
6.00 & 93 & 660 & 36 & 5:100 &
\begin{tabular}{c} LC–ESI– \\ MS/MS \\ \end{tabular} & 2971.02 & [58] \\ \hline \hline \end{tabular} Abbreviations: HPLC—high-performance liquid chromatography; LC–ESI–MS/MS—liquid chromatography-electrospray ionization tandem mass spectrometry; T—temperature; UHPLC—ultra-high-performance liquid chromatography.  
\end{table}
Table 7: French press method—brewing parameters and caffeine content.  
between the solvent (water) and the extracted material (coffee) leads to increased diffusion of soluble compounds, including caffeine.  
The water temperatures used in the AeroPress method were the same (93 \({}^{\circ}\)C), except for one study where the temperature was 88 \({}^{\circ}\)C and one of the lowest caffeine values was recorded there [46].  
The coffee-to-water ratio was similar in all studies, ranging from 6:100 to 7:100, so it can be assumed that this parameter did not significantly affect the variation in caffeine content.  
The most significant influence on caffeine content may have been the brewing time in the AeroPress method, while the other parameters were similar.