Abstract:The composition of peppermint essential oil was analyzed by gas chromatography-mass spectrometry (GC-MS). Using pseudo-ternary phase diagrams, the effect of various cosurfactants (ethanol, n-propanol, and n-butanol) on the phase behavior of the food-grade microemulsion system for peppermint essential oil using Tween 80-water was studied. In this study, the density, particle size, and pH value of the microemulsion, as well as its antimicrobial activity against Saccharomyces cerevisiae in NYDB medium and various drinks, were determined. The mechanism of the antimicrobial action of the microemulsion against Escherichia coli was primarily evaluated based on a cell membrane permeability assay. The results showed that the major components of peppermint essential oil were menthol (30.67%), and menthone (26.89%). Ethanol had the best solubilizing effect as a cosurfactant. The average particle sizes for two formulations (ME1, oil/ethanol = 1:1 and ME2, oil/ethanol = 1:3) were 66.57 nm and 55.63 nm, respectively. ME1 had higher antimicrobial activity and a better suppression effect against S. cerevisiae in clear apple juice. The minimum bactericidal concentration (MBC) was 64 μL/mL after cultures were grown at 28 ℃ for 48 h. When culturing with 5-fold diluted ME1 at 37 ℃ for 75 min, the leakage of E. coli nucleic acids was 51.68%. The microemulsion solution could kill E. coli by releasing nucleic acids and increasing the permeability of the E. coli cell membrane.
