Characterization of Oregano (Origanum vulgare) essential oil and definition of its antimicrobial activity against Listeria monocytogenes and Escherichia coli in vitro system and onto foodstuff surfaces

First aims of this research were the characterization of Oregano (Origanum vulgare) essential oil and the definition of its minimum inhibitory concentration against the pathogenic species Listeria monocytogenes and Escherichia coli. Moreover, the oregano essential oil antimicrobial activity was tested against these pathogenic species, inoculated onto wood and stainless steel surface. The GC/MS profile of Oregano essential oil revealed the presence of 34 compounds, principally terpinolene, carvacrol and p-cymene accounting for about 70% of the total area of the identified molecules. Oregano essential oil showed an higher antimicrobial activity against L. monocytogenes with respect in comparison to E. coli. In fact, the L. monocytogenes minimum inhibitory concentration ranged between 125 and 200 mg/L while those for E. coli ranged between 250 and 350 mg/L. Regarding the decontamination efficacy, the washing of the two surfaces with oregano fastened the viability decrease of both the inoculated microorganisms over time. This phenomenon was more pronounced for wood compared to steel. The data obtained suggested the great potential of this essential oil to be employed, in alternative to traditional chemicals, as sanitizing strategy for surfaces