A Study on chemical composition and antimicrobial activity of essential oil of Mentha longifolia L. and Cuminum cyminum L. in soup

Plant essential oils are increasingly used as natural food preservatives. Understanding their chemical composition and their antimicrobial activity in the context of food health and safety seems indispensible. In the present study the chemical composition of essential oils of Mentha longifolia L. and Cuminum cyminum L.، which were obtained using a Clevenger apparatus، was analyzed by GC/MS. The anti-microbial effect on growth of Bacillus cereus and Bacillus subtilis in different concentrations during 15 days incubation at 8 and 25°C was done in commercial barley soup. The taste acceptability of these essential oils was also assessed. The result indicated pulegon with 31. 54% and cuminaldehyde with 29. 02% were the most compounds found in Mentha longifolia L. and Cuminum cyminum L.، respectively. These essential oils at the 8°C showed significant reduction of bacterial count. The lowest concentration of the essential oils inhibited bacterial growth compared to the controls. Essential oil of Mentha longifolia L. showed more antibacterial activity compared to Cuminum cyminum L. essential oil in similar concentrations. On the other hand، Bacillus cereus was more sensitive to these essential oils than Bacillus subtilis. A concentration of 0. 15 µg ml-1 of these essential oils showed the maximum taste acceptability. This study clearly demonstrated that these essential oils could be used in some food systems without any undesirable palatability.