Preparation characteristics of monodisperse oil-in-water emulsions by microchannel emulsification using different essential oils

- Microchannel (MC) emulsification was used to droplets of different essential oils.
- Lemongrass oil, lemon oil and limonene were used as essential oils.
- Monodispersed essential oil-in-water (O/W) emulsions were obtained.
- Droplet generation behaviour depended on the essential oil and emulsifier types.
- Lemongrass oil mixtures were successfully used for MC emulsification.

In this study, MC emulsification was used for obtaining monodispersed essential oil-in-water (O/W) emulsions. The essential oils used were lemongrass oil (LGO), lemon oil (LO), and (R)-(+)-Limonene (LMN). Sodium dodecyl sulphate (SDS), Tween 20, and bovine serum albumin (BSA) were used as hydrophilic emulsifiers. Spontaneous diffusion of Tween 20 aqueous solution into LGO caused generation of the oil droplets containing smaller aqueous ones. The use of BSA resulted in wetting of the channel when formulating LGO droplets, unlike SDS and Tween 20. Monodispersed essential O/W emulsions with an average droplet diameter (davg) of 23-30 μm and a coefficient of variation (CV) of <5% were observed regardless of the essential oil and emulsifier types. LGO was also diluted with different triglyceride oils at a mixing ratio of 25-75 g/100 g. The droplet generation behaviour changed slightly after each dilution. The advantage of using an oil mixture is that less aqueous phase is diffused into the dispersed phase and that more stable emulsification is obtained. The resultant O/W emulsions were monodisperse with a davg of 20-30 μm and CV of <5%.