Antimicrobial activity of rosemary [Rosemarinus officinalis L] against food related bacteria in medium and food model systms

ABSTRACT

Rosemary was tested against various food-borne bacteria. Most bacteria showed high sensitivity to the spice when it was applied at concentration up to 2% . In agar media results indicated that a concentration as low as 0.3% was sufficient to inhibit the growth of some bacterial strains. When the antimicrobial activity of rosemary was evaluated against S.aureus [inoculum size-Slog CFU/g] in minced beef stored at 7°C, only a spice level of 1% reduced the pathogen population significantly but total elimination was not chieved. In boiled rice no or a slight reduction in pathogen population was observed in samples stored at refrigerated temperature [7°C]. However a concentration as low as 0.3% of rosemary was sufficient to declined the pathogen counts by-2 log cycles when tomato sauce samples inoculated with pathogen were stored at either 7 or 27°C for 3 days. There was evidence that low pH enhanced the antibacterial activity of rosemary whereas high protein and fat content reduced the effect of spice. As rosemary withstands heat treatment it could be a useful preservative agent in the food that pasteurized in their final package