Physicochemical, antioxidant, antibacterial and antibiofilm activity of Carum copticum essential oil nanoemulsion on Escherichia coli O157:H7 and Listeria monocytogenes.

Carum copticum essential oil (CEO) is used to prevent the growth of food-borne pathogens. The Carum copticum essential oil nanoemulsion (CEON) was prepared using low energy sonication at 0, 2.50, 5.00 and 10 min based on surfactant to-oil ratio (SOR=1). Chemical composition, antimicrobial and antibiofilm properties of CEON were examined. Our data showed that the average diameter of the droplets of CEON was between 46.89 and 120.90 nm. The MICs of CEON and CEO against E. coli O157:H7 and L. monocytogenes were tested. L. monocytogenes was more sensitive than E. coli O157:H7. The sonication time and the total viable bacteria (TVC) in the study were inversely related to each other. Furthermore, CEON at the 4.00 × MIC concentration and contact time of 20 min caused 77.14% and 67.03% reduction of E. coli O157:H7 and L. monocytogenes biofilms, respectively. The antibiofilm activity of CEO was significantly lower than CEON and caused a 62.60% and 43.86% reduction of E. coli O157: H7 and L. monocytogenes biofilms, respectively. The results showed that CEON produced by low energy sonication would have a higher antibacterial efficiency than non-encapsulted essential oil.