Preparation and characterization of blended cloves/cinnamon essential oil nanoemulsions

Blended cloves/cinnamon essential oil nanoemulsions were prepared using Tween 80 and ethanol as surfactant and cosurfactant respectively. The preparation process was optimized via a pseudo-ternary phase diagram. The nanoemulsion showed a steady state with an average particle size of 8.69 nm under the surfactant to cosurfactant ratio (Km) of 3:1 and oil to the mixed surfactant/cosurfactant ratio of 1:9. The nanoemulsion was stable after centrifuging at 10,000 rpm for 20 min, stored at 60 °C for 1 month, or even heated at 80 °C for 30 min, respectively. Compared with the non-nanoemulsion counterparts, the nanoemulsion showed higher antimicrobial activity against four tested microorganisms of Escherichia coli, Bacillus subtilis, Salmonella typhimurium, and Staphylococcus aureus, even at far lower concentrations. Furthermore, the addition of the cloves/cinnamon nanoemulsion in a model food of mushroom sauce did not alter its major flavor, except offered some attractive fragrant flavors. This research suggested that the blended cloves/cinnamon essential oil nanoemulsions have the potential to be developed as a natural antimicrobial agent in food industry.