Effect of different concentrations of Zataria multiflora Boiss. essential oil, nisin, and temperature on time to detection of Bacillus cereus

Plant essential oils are known to exhibit antimicrobial activities. Unfortunately, addition of high concentrations of the esesntial oils may cause undesirable flavor in food products . Therefore, they are being used in combination with other natural antibacterial agents such as bacteriocins and some other treatments (e.g. low temperatures). In this study combined effects of three concentrations of Zataria multiflora Boiss. essential oil (ZMEO) (0, 0.03, and 0.06 %), three concentrations of nisin (0, 0.5, and 2.5 ʽg/ml) and three incubation temperatures (10, 25 and 35 °C) on time to detection (TTD) of Bacillus cereus were evaluated in Brain Heart Infusion broth during 43 days. The results of this study showed that TTD was significantly affected (p<0.01) by the different concentrations of ZMEO alone or in combination with nisin (p> 0.05). The temperature also had significant effects on TTD of B. cereus. In conclusion, the combination of ZMEO, nisin with low temperatures may be useful for inhibiting the growth of B. cereus in foods.