In vitro Assessment of the Antibacterial and Antioxidant Properties of Essential Oils

Background: Outbreaks of foodborne diseases cause substantial economic losses. Universities, research institutes and the food industry are increasing their efforts to enhance food safety worldwide. In this context, the study of essential oils as natural antimicrobials and antioxidants for use in foods has become increasingly important. Methods: The volatile composition and antioxidant and antibacterial activity of Pelargonium graveolens, Cymbopogon citratus, Citrus bergamia, Rosmarinus officinalis and Mentha piperita essential oils were evaluated. Results: The essential oils showed 80.5 to 95.0% of monoterpenes, but with different profiles. The free radical scavenging activity by the DPPH assay ranged from 3.53 to 68.55% and the total antioxidant potential measured by FRAP ranged from 1.28 to 94.61 mmol TE g-1. The antioxidant activity (FRAP and DPPH assays) of the essential oils followed the order: C. citratus > M. piperita > P. graveolens > C. bergamia > R. officinalis. In general, when the pH tended to neutrality a higher concentration of essential oil was needed to inactivate the microorganisms. The C. citratus oil presented interesting results regarding the inhibition of both strains of S. aureus, showing a lower MIC50 value and Minimum Bactericidal Concentration (MBC) in the concentrations evaluated for E. coli and S. enterica. Conclusion: The results suggest that C. citratus essential oil has potential as an antibacterial and antioxidant agent.