Background: Vegetable essential oils and its components have anti-bacterial known effects. The aim of this study was to evaluate different concentrations of essential oils of thyme and mint on survival rate of Escherichia coli O157:H7 in traditional Lighvan cheese during ripening. Methods and findings: Essential oils were extracted using Kelevenger apparatus. To determine the essential oil concentration in terms of organoleptic, sensory evaluation was conducted by a test panel. Cheese samples prepared with the help of local manufacturers based in the village of Lighvan in triplicates, including zero and 100 and 200 ppm from essential oils of thyme and mint separately and doses of 103 and 10 5 cfugr-1 from the E. coli O157:H7 bacterium. In zero, 30, 60 and 90 days of ripening period, the number of E. coli O157:H7 studied in traditional Lighvan cheese samples. The results showed that the use of essential oil of mint and thyme with concentrations of 100 and 200 ppm compared to non-oil samples, reduced the log mean of the number of E. coli O157:H7 significantly (P<0/05). Also, the cheese storage time had a significant effect in reducing the log mean of the number of E. coli O157:H7 (P<0/05). Conclusion: The general results show that essential oil of Mint and Thyme can be used as a natural preservative and flavoring in the traditional Lighvan cheese but should be used in concentrations such that lacks no adverse effects on the taste and smell of food.
Mohammad Bafande Zendeh, Vadood Razavilar, Hamid Mirzaei, Mohammad Reza Ehsani, Khosrow Mohammadi