Antimicrobial effect of Origanum vulgare (L.) essential oil as an alternative for conventional additives in the Minas cheese manufacture

The presence of fungi and contaminating bacteria in ripened cheeses is a major concern for the dairy industry worldwide. Therefore, the objective of this study was to evaluate the antimicrobial activity of oregano essential oil (Origanum vulgare L.) (OEO) against bacteria (Escherichia coli and Staphylococcus aureus) and filamentous fungi on cheeses during ripening. For this purpose, Minas cheeses were produced and artificially contaminated with strains of enteropathogenic E. coli, multidrug-resistant S. aureus, and the fungi Aspergillus flavus, Fusarium oxysporum, and Penicillium citrinum. The experiments were performed with Minas cheeses containing OEO, natamycin and nisin, in challenge tests against bacteria and fungi. OEO at a concentration of 0.02% (v/v) demonstrated antibacterial and antifungal activity, with total elimination of all the tested strains until the sixth day of ripening, besides inhibiting the germination of fungal spores. The pH and moisture of the samples were not significantly affected by the addition of OEO at the tested concentration. Thus, OEO at a concentration of 0.02% (v/v) used in the production of Minas cheese was efficient in controlling pathogenic and multidrug-resistant microorganisms and toxigenic fungi during ripening, and its use presents a potential alternative for microbial control.