Antibacterial Effect of Teucrium polium Essential Oil and Lactobacillus casei Probiotic on Escherichia coli O157:H7 in Kishk

Abstract

Background and Objective: In recent years, there has been a rapid development in prevention of bacterial growth and spoilage in foods by the application of preservatives. Essential oils, which are known to be harmless for human, have shown positive health effects in addition to their preservative role. Likewise, probiotics exert improvement in both food product and health level of consumers. With reference to these it is important to do more research on various effects of endemic essential oils on traditional food products. A survey was carried on effect of essential oil and combination of essential oil and probiotics on growth of Escherchia coli O157:H7.Material and Methods: Kishk samples treated with Teucrium polium essential oil (75 and 150 mg l-1) and Lactobacillus casei (108 -109 CFU ml-1) were stored up to 20 days at 4°C and the effect of Teucrium polium essential oils and probiotic fermentation on Escherchia coli O157:H7 counts were investigated.Results and Conclusion: Teucrium polium essential oils and probiotic fermentation reduced the number of Escherichia coli during the cold storage time. The combination of Teucrium polium essential oil and probiotics showed stronger effect rather than individually added. Initial count of inoculated Escherchia coli was 6.39 log CFU g-1. Essential oil compounds of Teucrium polium included Spathulenol, Epizonaren and Bicyclo hept-3-en-2-ol in 18.39, 9.62 and 6.76%, respectively. After 20 days storage at 4°C, the number of Escherchia coli in probiotic, combination of probiotic and essential oil (150 mg l-1) and control samples decreased from 6.39 log CFU g-1 to 4.95, 4.30 and 5.8 log CFU g-1, respectively. An increase in acidity and decrease in pH were observed for all samples (p≤0.05). Based on organoleptic tests, the most accepted sample was included 75 ppm of essential oil and probiotic. According to the antibacterial effect of essential oils extracted from plant and probiotic fermentation, it was predictable that they could decline the Escherchia coli count especially in fermented dairy products. Also, due to its probiotic nature, Kishk would bring numerous health advantageous for consumer.