Bactericidal Effect of Some Herbal Extracts against Meat-Borne Staphylococcus aureus

Natural extracts of green tea, rosemary and ginger were evaluated for their effects on the growth and survival of Staphylococcus aureus artificially inoculated into minced meat. Fresh minced meat samples were inoculated with (~ 7 log CFU/g) of S. aureus and left for 30 minutes at room temperature to allow attachment and absorption of bacteria; where, the initial count of S. aureus in minced meat samples immediately after inoculation was 7.66 log CFU/g. Natural extracts of green tea leaves, rosemary and ginger roots were added to the minced meat samples to achieve final concentrations of 0.7, 1 and 2% (%v/g). Sensory profile and S. aureus counts were conducted on zero, 3rd, 5th, 7th and 9th day during cold storage at 4°C. Initial counts of S. aureus in minced meat samples decreased following treatment with 2% of green tea, rosemary and ginger extracts at 3rd day by 6.27, 25.46 and 30.81%, respectively. Ginger extract (2%) showed the best antimicrobial effect with extension of shelf-life of refrigerated minced meat to nine days compared to all groups especially control untreated group, followed by rosemary 2% (till 7th day). As compared with several other mild preservation procedures, treatment with green tea, rosemary and ginger extracts is inexpensive and uncomplicated method. Results of the present study are envisaged to be useful for commercial applications of these plant extracts as potential food biopreservatives and anti-S. aureus agents in minced meat and other foods, depending upon the desired flavor of such products.