ANTIBACTERIAL AND ANTI-OXIDANT ACTIVITIES OF LAUREL OIL AGAINST Staphylococcus aureus AND Pseudomonas fluorescence IN Oreochromis niloticus FILLETS

Abstract

Laurus nobilis L. commonly known as Bay belonging to the family Lauraceae, is one of the most useful plant used in foods as a spice in Mediterranean cookery. This study was designed to evaluate the antibacterial and anti-oxidant activities of different concentrations of laurel essential oil (0.5%, 1%, 1.5%) against two bacterial strains "Staphylococcus aureus as food poisoning bacteria and Pseudomonas fluorescence as food spoilage bacteria" in order to enhance fish safety and increase shelf life. A total of 80 samples of freshly dead Oreochromis niloticus fish were collected after experimental infection with the two bacterial strains followed by treatment with different concentrations of laurel essential at different storage time at chilling temperature. The results showed that laurel essential oil was efficient against the tested bacteria, but varied in its antibacterial activity as follows; the highest reduction percent of S. aureus and P. fluorescence at rate of 99.97% and 94.5% was detected 6 days after laurel oil treatment, respectively, and reached 100% 9 day after oil treatment at the same concentration. While the lowest value was obtained with 0.5% concentration. Laurel oil (1.5%) also showed a significant decrease in pH, TNB-N and TBA. Based on the obtained data, it could be concluded that, laurel essential oil has strong antibacterial and antioxidant activity against the tested bacteria, so that it can be used as natural food preservatives alternatives to other synthetic agents to keep quality and increase fish shelf life.Key words: Laurus nobilis; essential oil; antibacterial activity; fish shelf-life; food safety