Comparative antimicrobial activity of Zataria multiflora essential oil nanoformulations against foodborne pathogens

Abstract

Abstract Foodborne diseases caused by microbial contamination, as a profound global health challenge, driving the search for natural antimicrobial compound. This study investigated the antimicrobial potential of Zataria multiflora essential oil ( Z. multiflora EO) encapsulated in alginate nanoparticles (Alg-EO), chitosan nanoparticles (Chi-EO), and nanoemulsions (NE-EO) against major foodborne pathogens: Escherichia coli ( E. coli ), Salmonella Typhimurium ( S. Typhimurium ), Pseudomonas aeruginosa ( P. aeruginosa ), and Staphylococcus aureus ( S. aureus ). The nanoformulations were prepared using spontaneous emulsification and ionic gelation techniques and subsequently characterized for size, zeta potential, and encapsulation efficiency via dynamic light scattering (DLS) and ATR-FTIR spectroscopy. Finally, the antibacterial activity of the nanoformulations was evaluated via the microdilution method. Results revealed that Chi-EO exhibited the smallest hydrodynamic diameter (129 nm) and highest negative zeta potential (− 37 mV), whereas Alg-EO and NE-EO measured 152 nm (− 28 mV) and 144 nm (24 mV), respectively. Notably, Chi-EO demonstrated strongest antimicrobial efficacy, with the lowest IC50 values against S. aureus (321 μg/mL), S. Typhimurium (460 μg/mL), E. coli (367 μg/mL), and P. aeruginosa (504 μg/mL). These findings highlight chitosan nanoparticles serve as an efficient delivery system for Z. multiflora EO, offering a natural and potent approach to improving food safety and extending shelf life.