Antimicrobial effect of Mentha piperita L. essential oil on Escherichia coli O۱۵۷:H۷ during manufacture and ripening of white brined cheese

Mentha piperita L is extensively used as flavoring agent in dairy products. Also it has antimicrobial effects on the pathogenic bacteria which cause some food borne diseases. The aim of this study was to evaluate the antimicrobial effect of this plant’s essential oil on Escherichia coli O۱۵۷:H۷ in white brined cheese, considering the organoleptic properties of cheese. The essential oil of Mentha piperita L.was obtained by hydrodistillation and analyzed by GC/MS. Preliminary sensory tests were carried out to establish the upper level of the essential oil incorporation. At the end of storage time, evaluation of the sensory characteristics of the supplemented cheeses suggested that, Mentha piperita L.essential oil’s concentrations more than ۲۰۰ ppm in cheese milk had adverse effects on the taste and odor of cheeses. Therefore, further examinations were carried out with ۰, ۱۰۰, ۱۵۰ and ۲۰۰ ppm concentrations. The inhibitory effects of different concentrations of the Mentha piperita L. essential oil on E. coli O۱۵۷:H۷ were determined by enumeration of the microorganism on selective media and comparing the bacterial counts in different groups. The inhibitory effect of Mentha piperita L. essential oil atconcentration of ۲۰۰ ppm was higher compared to its lower concentrations and also compared to the control groups. No significant difference (P > ۰.۰۵) was observed between the pH values of control groups and treated samples. Incorporation of Mentha piperita L. essential oil at concentration of ۲۰۰ ppm into cheese milk had significant antibacterial activity .However, when these kinds of essential oil has to be recommended for cheese safety, issue of strong taste and smell should be addressed.

Keywords:

Escherichia coli O۱۵۷:H۷ , Mentha piperita L. , Essential oil , White brined cheese