Influence of primary homogenization step on microfluidized emulsions formulated with thyme oil and Appyclean 6548

Abstract

This contribution deals with the development of emulsions formulated using thyme essential oil and a new biomass-derived surfactant. In addition, this work extends our knowledge concerning the factors that can influence stability and droplet size distributions of microfluidized emulsions, such as the geometry of the rotor–stator used and the homogenization rate in the primary homogenization. Stable thyme oil-in-water emulsions (30 wt%) containing submicron droplets were formed. Interestingly, laser diffraction results reveal that mean droplet sizes are mainly controlled by homogenization rates and polydispersity by the rotor–stator geometry used in the first step of homogenization. In addition, higher droplet sizes for pre-emulsions seem to be a key factor in order to reduce both the degree of recoalescence and the size of the droplets in the second homogenization step. Furthermore, higher droplet sizes in the pre-emulsion favour higher physical stability of the final emulsions. Finally, this research highlights the importance of controlling primary homogenization conditions for the physical stability of microfluidized emulsions that contain natural ingredients.