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

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.