# Antioxidant Activity of Coffee Components Influenced by Roast Degree and Preparation Method
## 3 Results and Discussion
### Antioxidant Activity of Coffee Extracts
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multicolumn{2}{c}{**Brew Type**} & \multicolumn{2}{c}{**Beans**} & \multicolumn{2}{c}{**Epresso**} & \multicolumn{2}{c}{**Moka brew**} \\ \hline \multicolumn{2}{c}{**Roast Degree**} & \multicolumn{1}{c}{**Medium**} & \multicolumn{1}{c}{**Dark**} & \multicolumn{1}{c}{**Medium**} & \multicolumn{1}{c}{**Dark**} & \multicolumn{1}{c}{**Medium**} & \multicolumn{1}{c}{**Dark**} \\ \hline \multirow{3}{*}{\% of inhibition} & CBA & 74.23 \(\pm\) 0.84 d & 74.08 \(\pm\) 1.29 d & 78.12 \(\pm\) 2.07 c & 71.43 \(\pm\) 1.66 b & 60.80 \(\pm\) 1.61 a & 55.49 \(\pm\) 3.69 a \\ \cline{2-8}  & Autoxidation & – & – & 265.04 \(\pm\) 7.02 c & 242.35 \(\pm\) 5.64 b & 240.64 \(\pm\) 6.38 ab & 226.64 \(\pm\) 5.13 a \\ \hline \multirow{3}{*}{
\begin{tabular}{c} Antioxidant \\ activity [mg \\ Trolox/portion] \\ \end{tabular} } & CBA & 54.30 \(\pm\) 1.41 d & 51.27 \(\pm\) 0.96 c & 50.38 \(\pm\) 1.13 c & 51.36 \(\pm\) 0.52 c & 42.03 \(\pm\) 0.45 a & 45.37 \(\pm\) 0.13 b \\ \cline{2-8}  & Autoxidation & – & – & 389.94 \(\pm\) 8.73 ab & 397.52 \(\pm\) 4.01 bc & 379.52 \(\pm\) 4.05 a & 409.68 \(\pm\) 1.19 c \\ \hline \multicolumn{8}{c}{Results shown as mean values \(\pm\) standard deviations. In rows, values with different letters are significantly different (\(p\) < 0.05; n \(\geq\) 3). To create homogenous groups, [PERSON]’s HSD test was used.} \\ \end{tabular}
\end{table} 
Table 4: Content of phenolic compounds and antioxidant activity measured by HAT-based methods. brewing methods may not behave in a similar way in antioxidant experiments based on different mechanisms. Regarding the roasting degree effect on the antioxidant activity of coffee brews, the information in the literature is not explicit. [PERSON] et al. [33], examining the activity of aqueous coffee extracts, showed both an increase and a decrease in the values with the darker degree of roasting in various analytical methods. Similar observations were reported in later publications [11; 31; 33; 34; 35; 36; 40]. Initial changes regarding antioxidant activity might be connected to the release of low-molecular-weight phenolic compounds in the early stage of roasting, while the decrease observed later might be associated with their degradation and/or structural changes [5; 30; 37]. [PERSON] et al. [36] also observed a decrease in the antioxidant activity of coffee with a darker roast. They also observed the formation of some phenolic compounds during roasting, e.g., gallic acid, pyrogallol or purpurogallin, and suggested that it might compensate for the decrease in antioxidant activity of coffee from the loss of chlorogenic acid. Studies using hot and cold brews [19] showed that the degree of roasting had a significant negative effect only in the case of cold brew. In hot coffee brews, an increase in antioxidant activity with a higher degree of roast was reported using 2,2,6,6-tetramethyl-1-piperidin-1-oxyl stabilized radical with electron paramagnetic resonance spectroscopy. The issue of factors influencing the antioxidant activity of coffee is, therefore, difficult to unequivocally solve. Not only the issues related to the coffee bean and its treatment but also the choice of the analytical method can have a significant influence on the final result. Using statistical analysis, the correlation of the results of antioxidant activity with the content of phenolic compounds in coffee was checked (the content of melanoidins was omitted due to the small amount of data). In the case of the results expressed as mg Trolox per 100 g DM, a strong positive correlation was found between the content of phenolic compounds and the results obtained with the CUPRAC and ABTS methods (\(\mathrm{r_{P}}=0.8282\) and \(\mathrm{r_{P}}=0.8975\), respectively; \(p\leq 0.001\)).