Physicochemical and Antimicrobial Properties of Hydroxypropyl Methylcellulose-Cinnamon Essential Oil Emulsion: Effects of Micro- and Nanodroplets

Emulsion is an efficient encapsulation tool for enhancing the functional properties of essential oils (EOs). Herein, two two-dimensional cinnamon essential oil emulsions (from micro- to nanoscales) were emulsified by hydroxypropyl methylcellulose, and their antimicrobial and physicochemical properties were investigated. For the models of Escherichia coli CGMCC 1.0907, Salmonella enterica subsp. Enterica serovar Typhi (CICC 10867), Staphylococcus aureus CGMCC 1.0089, and Listeria monocytogene CGMCC 1.9144, the minimum inhibitory concentration (MIC) of the nanoemulsion was 31.25 mu L/mL compared to that of the microemulsion (62.5-125 mu L/mL) and pure oil (125-250 mu L/mL), indicating the superiority of nanoemulsion as an antibacterial agent. The results showed that the highest activity was seen in the gram-positive L. monocytogenes whereas the lowest was in the gram-negative S. enterica. The identified properties of HPMC (hydroxypropyl methylcellulose) provide the potential for emulsifying and enhancing essential oils in light industries, especially for food processing.