SYNERGISTIC ANTIBACTERIAL ACTIVITY OF IRRADIATED AND NON IRRADIATED CUMIN, THYME AND ROSEMARY ESSENTIAL OILS

Abstract

The study aimed to evaluate the efficacy of plant essential oils and their mixtures and to investigate the effect of g-irradiation on their antibacterial activity. About 2 kGy (C 2) and 4 kGy (C4) in cumin essential oil, 4 kGy (T4) in thyme essential oil, and 6 kGy (R6) in rosemary essential oil were the effective antibacterial dose against Escherichia coli, Salmonella typhimurium, Bacillus cereus and Staphylococcus aureus. The checkerboard method was used to quantify the efficacy of mixtures made from cumin, thyme and rosemary. Fractional inhibitory concentrations were calculated and interpreted as synergy, addition, indifference or antagonism. Most of the mixtures showed indifference efficacy against selected strains. (R6 ¥ T4) and (C4 ¥ R6) represented additive efficacy against B. cereus and S. typhimurium, respectively. Synergistic effect was observed against B. cereus and E. coli in (C0 ¥ R0). (C2 ¥ T4) represented a higher minimum inhibitory concentration than (C0 ¥ T0). The mixtures of essential oils either irradiated or nonirradiated could be used to minimize essential oil concentrations and to reduce any adverse sensory impact on food.