# Plant Organic Acids as Natural Inhibitors of Foodborne Pathogens
## 3 Results  
### Antibacterial and Antifungal Activity  
Studies have shown that benzoic acid and salicylic acid exhibit the best activity against foodborne bacteria, with an average MIC of less than 1 mg/mL. Acetic acid, chlorogenic acid, formic acid, malic acid, nicotinic acid, and rosmarinic acid demonstrated slightly weaker activity, with average MICs between 1 and 2 mg/mL. Many other acids (ascorbic, caproic, citric, fumaric, oxalic, succininic, tannic, tartaric, and valeric acid) had moderate activity against bacteria. The weakest antibacterial activity was observed in aminoacetic, glutamic, oleic, and palmitic acids, with average MICs ranging from 7.5 to 70.83 mg/mL. Considering that the average MIC for cotenidine (positive control) is 0.11 mg/mL, it is evident that the tested organic acids are active at concentrations approximately 10,000 times higher (Table 2). \begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Organic Acid** & \begin{tabular}{c} _Staphylococcus_ \\ _aureus_ \\ \end{tabular} & \begin{tabular}{c} _Escherichia_ \\ _coli_ \\ \end{tabular} & \begin{tabular}{c} _Listeria_ \\ _monocytogenes_ \\ \end{tabular} & \
\begin{tabular}{c} _Salmonella_ \\ **Typhimuriumurium** \\ \end{tabular} &
\begin{tabular}{c} **Mean MIC \(\pm\) SD for** \\ **All Bacteria** \\ \end{tabular} \\ \hline Acetic acid & 1.25 & 1.25–2.5 & 1.25 & 2.5 & 1.72 \(\pm\) 0.65 \\ \hline Aminoacetic acid & 100 & 50 & 50 & 50–100 & 70.83 \(\pm\) 25.75 \\ \hline Ascorbic acid & 1.25 & 1.25–2.5 & 2.5 & 5 & 2.66 \(\pm\) 1.56 \\ \hline Benzoic acid & 0.63 & 0.31–0.63 & 0.31–0.63 & 0.63–1.25 & 0.63 \(\pm\) 0.29 \\ \hline Caproic acid & 5 & 2.5 & 2.5 & 5 & 3.75 \(\pm\) 1.34 \\ \hline Chlorogenic acid & 1.25–2.5 & 1.25 & 1.25–2.5 & 1.25–2.5 & 1.72 \(\pm\) 0.65 \\ \hline Citric acid & 5 & 2.5 & 1.25–2.5 & 2.5 & 2.97 \(\pm\) 1.33 \\ \hline Formic acid & 1.25 & 1.25 & 1.25 & 2.5 & 1.56 \(\pm\) 0.58 \\ \hline Fumaric acid & 1.25–2.5 & 2.5 & 2.5–5 & 2.5 & 2.66 \(\pm\) 1.04 \\ \hline Glutamic acid & 5 & 5 & 10 & 10 & 7.50 \(\pm\) 2.67 \\ \hline Malic acid & 2.5 & 0.63 & 0.63–1.25 & 1.25 & 1.33 \(\pm\) 0.78 \\ \hline Nicotinic acid & 1.25–2.5 & 0.63–1.25 & 0.63–1.25 & 1.25 & 1.25 \(\pm\) 0.56 \\ \hline Oleic acid & 5 & 10 & 5 & 10 & 7.50 \(\pm\) 2.67 \\ \hline Oxalic acid & 2.5–5 & 0.63–1.25 & 1.25–2.5 & 2.5 & 2.27 \(\pm\) 1.33 \\ \hline Palmitic acid & 20–50 & 20–50 & 20 & 20–50 & 27.5 \(\pm\) 13.57 \\ \hline Rosmarinic acid & 2.5 & 1.25 & 1.25–2.5 & 1.25–2.5 & 1.88 \(\pm\) 0.67 \\ \hline Salicylic acid & 0.63–1.25 & 0.31–0.63 & 0.63 & 0.63 & 0.67 \(\pm\) 0.26 \\ \hline Succinic acid & 2.5–5 & 0.63–1.25 & 1.25–2.5 & 2.5 & 2.27 \(\pm\) 1.33 \\ \hline Tannic acid & 2.5–5 & 1.25–2.5 & 0.63–1.25 & 2.5 & 2.27 \(\pm\) 1.33 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: The minimal inhibitory concentrations (MIC) of the organic acids and cotenidine against foodborne bacteria. MIC values are presented in mg/mL. The last column shows the mean values and standard deviation (SD) for all readings for a given acid. In the study, MIC values were determined against two foodborne fungi, _Geotrichum candidium_ and _Penicillium candidium_. For all acids tested, the antifungal activity was weaker compared to bacteria. The acetic, benzoic, caproic, chlorogenic, citric, formic, rosmarinic, and valeric acids exhibited the best activity, with mean MICs < 10 mg/mL. Fumaric, oxalic, and tannic acids showed moderate activity, with mean MICs between 10 and 20 mg/mL. Unfortunately, many acids such as ascorbic, malic, oleic, palmitic, succinic, and tartaric had very weak antifungal activity, with MICs > 20 mg/mL, while aminoacetic and glutamic acids had MICs > 100 mg/mL, indicating no activity (Table 3, Figure 1).