Antimicrobial action of Oregano, Thyme, Clove, Cinnamon and Black pepper essential oils free and encapsulated against foodborne pathogens

The antimicrobial properties of essential oils from spice and medicinal plants have aroused interest for their potential as an alternative to the use of chemical preservatives in foods. In this work, we studied the bacteriostatic and bactericidal effects of Oregano, Thyme, Clove, Cinnamon and Black-pepper essential oils (EOs) against strains of Staphylococcus aureus, Listeria sp, Escherichia coli and Salmonella sp. that contaminate food and cause Foodborne Diseases (FBD). The study was carried out with free EOs and in blends, to study the potential synergistic effect between them. Moreover, microcapsules containing oregano, thyme and clove EO were developed with different wall materials obtained by complex coacervation between three different polymers (chitosan, gelatin, and Arabic gum). Among the free EOs, cinnamon EO stood out in inhibiting the growth of all bacteria tested. The best combination was Oregano + Thyme, presenting a synergistic effect against the bacteria tested with a considerable reduction in the initial Minimum Inhibitory Concentration (MIC). Encapsulation positively influenced the inhibitory power of the oils by resulting in MICs lower or close to those of the oil in the free form. Given the above, we can conclude that the tested EOs perform well in inhibiting these pathogens and that their effect is potentiated when tested in combination.