In the past, several efforts have been made to find suitable substitutes for synthetic preservatives in meat products with fewer side effects on human health. Essential oils have gained worldwide interest due to their antimicrobial activity. The addition of these aromatic compounds to foods may be hampered by their strong sensory characteristics (taste and smell). The objective of this study was to evaluate the efficiency of five essential oils (EOs) (Ocimum basilicum L., Origanum vulgare L., Rosmarinus officinalis L., Salvia officinalis L., and Thymus vulgaris L.) against important foodborne pathogens. First, a microdilution assay was carried out to determine the minimal inhibitory concentration (MIC) of the EOs against Staphylococcus (Staph.) aureus ATCC 6538, Salmonella (S.) enterica subsp. enterica serovar Typhimurium ATCC 14028, and Escherichia (E.) coli ATCC 25922. Since the EOs inhibited the growth of these bacteria, their activity was studied in a real food matrix. The in vivo test was performed on the model of liver pâté: the homogenized and heat-treated samples were formulated with EOs at concentrations of 1 MIC and 2 MIC, inoculated with bacterial suspensions (105 CFU/g), packaged under vacuum, and stored at 4 ºC for 3 days. The addition of 2 MIC of thyme and sage oils showed a significant reduction in the viable counts of E. coli, S. Typhimurium, and Staph. aureus compared to the control samples.
Overall, this study demonstrated that thyme and sage EOs, as natural preservatives, had great potential to prevent the growth of important foodborne pathogens (E. coli, S. Typhimurium, and Staph. aureus) in liver pâté, but their efficiency was highly dose-dependent. However, the tested concentrations of EOs (1 MIC and 2 MIC) had an influence on the sensory characteristics of the finished products that may hinder their future applicability to improve the shelf-life of meat products. Therefore, further studies are required to clarify such an issue.