Effect of Zataria multiflora Boiss. essential oil, nisin, and temperature on time to the nearest visible growth detection of Escherichia coli O157: H7

Chemical additives and preservatives are usually integrated into food to diminish or decrease the risk of pathogenic or spoilage microorganisms. Unfortunately, some of these agents have harmful effects on consumers health. Therefore many researches have been done to replace the chemical preservatives with natural green ones especially plant essential oils and bacteriocins. In this study multifactorial 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 the nearest visible growth detection (TTD) of E.coli O157:H7 were investigated 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 whereas nisin did not show a significant inhibitory effect (p> 0.05). Also, the temperature had a significant effect on TTD of E.coli O157:H7. In conclusion, the combination of ZMEO with low temperatures may be practical for protecting food from the risk of E.coli O157: H7.

Effect of Zataria multiflora Boiss. essential oil, nisin, and temperature on time to the nearest visible growth detection of Escherichia coli O157: H7 Keywords:

E.coli O157: H7 , Nisin , Zataria multiflora , TTD