Evaluation of the antimicrobial effect of oregano essential oil (Origanum vulgare) on cooked mussels (Perna perna) experimentally contaminated with Escherichia coli and Salmonella Enteritidis

Seafood is a major group associated with foodborne illnesses, with Salmonella spp. and E. coli being pathogens of great importance. The use of natural preservatives, such as essential oils, is gaining traction in the food industry to combat pathogenic microorganisms. This study aimed to evaluate the antimicrobial activity of oregano essential oil (OEO) against pathogenic strains of E. coli and Salmonella Enteritidis, experimentally inoculated in mussels (Perna perna). The antagonism test for OEO against Salmonella Enteritidis and E. coli was conducted using the agar well diffusion method, and the Minimum Inhibitory Concentration (MIC) was determined by microdilution. Mussels were experimentally contaminated and treated with OEO, then stored at 5 °C and analysed over ten days. Results showed OEO effectively reduced bacterial counts, with higher efficacy against Salmonella Enteritidis, with an average count difference of 2.252 log CFU/g over the 10-day storage period. The study concludes OEO as a natural preservative, with its effectiveness dependent on oil concentration and microbial load.