Abstract

Antibacterial properties of essential oils (EOs) extracted from Salvia sclarea, Artemisia annua and Dracocephalum heterophyllum against 17 food borne pathogens was studied. EOs of the three plants showed a broad spectrum of antimicrobial activity with different degrees of inhibition against the tested Gram-positive and Gram-negative bacteria. EOs ofSalvia and Dracocephalum depicted bactericidal mode of action while that of Artemisiainhibited the bacteria with bacteriostatic mode. Salmonella enterica MTCC 733 was the most sensitive strain to Salvia, Artemisia and Dracocephalum EOs with minimum inhibitory concentration (MIC) values of 2000, 2000 and 8000 µg/ml, respectively. The antimicrobial activity of EOs individually and in combinations based on their respective MIC values against S. enterica was tested in raw chicken. Treatment of food sample with 20 times MIC value of S. sclarea, A. annua and D. heterophyllum EOs individually caused reduction of bacterial load to 3.36, 3.64 and 4.22 log cfu/g after 180 min. In contrast the bacterial cell loads reduced to an undetectable level by the combinative effect (Salvia + Dracocephalumand Salvia + Artemisia) of EOs at MIC value after 120 and 180 min, respectively. This study suggests that combinations of EOs could minimize application concentrations in real food system.

Key words: Antibacterial activities, essential oils, food-borne pathogens, fractional inhibitory concentration, minimum inhibitory concentration, Salmonella enterica.