Natural Honey-Propolis Combinations with Health-Promoting Potential: Antibacterial Activity Against Foodborne...

Background/Objectives: Natural products such as honey and propolis have been widely studied for their antimicrobial properties. Combining these substances has shown synergistic effects against foodborne pathogens and has also demonstrated promising results in previous applications on fermented meat products. This study evaluated the antibacterial potential of Spanish thyme (Thymus spp.) and chestnut (Castanea sativa) honeys, enriched with 10% ethanolic extract of propolis, against two major foodborne pathogens: Listeria monocytogenes and Clostridium perfringens. Methods: Antibacterial activity was assessed using broth microdilution assays and colony-forming unit (CFU) counts. The phenolic composition of the most active samples was characterized by LC-MS-Q/TOF and UPLC-PDA to identify and quantify the bioactive compounds. Results: All samples exhibited differential responses depending on the pathogen, with C. perfringens being the most susceptible. Propolis addition significantly enhanced the bactericidal response of honey against L. monocytogenes and C. perfringens (p < 0.05). This effect correlated with higher levels of antimicrobial phenolic compounds, particularly cinnamic acid derivatives, pinobanksin-3-O-hexanoside, sakuranetin, quercetin, and quercetin-3,7-dimethyl ether. Conclusions: These findings support the synergistic antibacterial potential of honey-propolis combinations, highlighting their application as natural preservatives for reducing the risk of foodborne diseases, as well as bioactive ingredients in nutraceutical formulations with antibacterial properties and additional health benefits.