Antimicrobial activity of Greek oregano and winter savory extracts (essential oil and SCFE) investigated by impedimetry

The inhibitory activity of the essential oil and supercritical fluid extract (SCFE) of Origanum vulgare subsp. hirtum (Link) letswaart and Satureja montana L. were tested by impedimetry on a number of food-borne bacteria and fungi. Both essential oil and SCFE of oregano had a significant growth-inhibitory effect against Escherichia coli, Pseudomonas fluorescens, Bacillus cereus and Aspergillus niger strains in 0.05 and 0.1% (v/v) concentrations. SCFE of oregano in 0.1% concentration proved to be able to inhibit growth of Saccharomyces cerevisiae. Winter savory extracts (essential oil and SCFE) had antimicrobial activity against Ps. fluorescens, S. aureus, B. cereus and A. niger at both concentrations. However, there was no significant difference in conductimetric detection times between control and winter savory-treated samples in case of E. coli and Sacch. cerevisiae. In general, the microorganism strains were more sensitive to oregano extracts than to winter savory extracts, and essential oils were more effective than SCFEs added in the same concentrations.