## 3 Results
### Stratification Meta-Analysis of MIC Values of Each Hop Compound
Similarly, the \(\alpha\) acid humulone showed comparable antimicrobial activities against food spoilage and non-food spoilage microorganism (43.35 and 33.75 \(\mu\)g/mL), while lupulone (beta-acid) showed significantly higher antimicrobial activity against non-food spoilage bacteria (4.20 compared to 12.40 \(\mu\)g/mL, respectively). Importantly, due to the small number of studies included, the last results should be considered with caution. For 48 h of treatment, xanthohumol showed enhanced antimicrobial activity against food spoilage compared to non-food spoilage microorganisms (23.46 and 54.32 \(\mu\)g/mL, respectively), as shown in Table 4 and Figure 6B. \begin{table}
\begin{tabular}{p{113.8 pt} p{56.9 pt} p{56.9 pt} p{56.9 pt} p{56.9 pt} p{56.9 pt} p{56.9 pt}} \hline \hline
**Compound** & **Time (h)** & \begin{tabular}{c} **Food** \\ **Spoilage/Non-** \\ **Food Spoilage** \\ \end{tabular} & **MIC** & **95\% CI** & \
\begin{tabular}{c} **Number of** \\ **Studies** \\ \end{tabular} &
\begin{tabular}{c} **Publication Bias** \\ **(p-Value)** \\ \end{tabular} \\ \hline \hline \multirow{2}{*}{**Flavonoids**} & 24 & Food spoilage & 22.81 & 11.54–34.08 & 33 & 0.550 \\  & & Non-food spoilage & 21.68 & 0.00–47.71 & 6 & 0.00 \\ \cline{2-6}  & 48 & Food spoilage & 242.25 & 9.61–474.88 & 26 & 0.00 \\  & & Non-food spoilage & 263.28 & 130.45–396.11 & 49 & 0.190 \\ \hline \multirow{2}{*}{Xanthohumol} & Xanthohumol & 24 & Food spoilage & 21.92 & 9.02–34.83 & 28 & 0.632 \\  & & Non-food spoilage & 21.68 & 0.00–47.71 & 6 & 0.00 \\ \cline{2-6}  & 48 & Food spoilage & 23.46 & 8.76–38.15 & 7 & 0.060 \\  & & Non-food spoilage & 54.32 & 48.10–60.54 & 40 & 0.643 \\ \hline \multirow{2}{*}{Catechin} & 48 & Food spoilage & 700.0 & 271.78–1128.2 & 7 & 0.265 \\  & & Non-food spoilage & 1192.0 & 658.25–1725.8 & 9 & 0.038 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Meta-analysis of MIC values of hop compounds and extracts stratified according to food spoilage microorganisms. Figure 6: Meta-analysis of MIC values for each hop compound against food-spoilage and non-food-spoilage microorganisms for 24 (**A**) and 48 (**B**) hours of incubation. Among the different types of extracts, hydroalcoholic extracts seemed to be more effective against food spoilage microorganisms for both 24 and 48 h of treatment. CO\({}_{2}\) extracts were less effective than hydroalcoholic extracts; however, 48 h of treatment resulted in higher antimicrobial effectiveness against non-food spoilage bacteria. Hydralcoholic extracts were more effective against food spoilage bacteria when tested for both 48 h (Table 4 and Figure 7). The MIC values for 48 h of treatment are expected to be lower than the MIC values for 24 h, because compounds have more time to exert their effect. However, it is important to note here that the tests for these different time points are performed with different microorganisms' species which profoundly respond in a completely different way (Table 4 and Figure 7). Finally, publication bias was tested, and we observed that it was more frequent in meta-analyses of studies assessing the MIC for 48 h of incubation (Table 4).