Stability of the PEG Fatty Acid Glycerides Based O/W Emulsions

In the present work, oil-in-water (O/W) emulsion systems were prepared by using the PEG-7 lauric acid glycerides as the emulsifiers and the liquid paraffin as the oil phase. The influence of processing parameters such as emulsification temperature, stirring speed, emulsifier concentration, oil-water volume ratio and polymer addition on the stability of the emulsion systems was investigated. In order to determine the optimal conditions for the preparation of the emulsion systems based on PEG-7 lauric acid glycerides, a laser drop size analyser and a rotational rheometer were used. As the stability of the O/W emulsion systems increased, the average droplet size of the O/W emulsions measured by the laser droplet size analyser became smaller and the viscosity, storage modulus and loss modulus of the O/W emulsions measured by the rotational rheometer became larger. The following optimal conditions were determined in this study: emulsification temperature 80°C, stirring speed 500 r/min, emulsifier concentration 5 wt%, oil-water volume ratio 1:1 and added amount of xanthan gum 0.2 wt%. The droplet morphology of the O/W emulsion prepared under the optimal conditions, which was characterised by a super high magnification microscope, is small. Furthermore, the long-term stability of the emulsion system prepared under the optimal conditions was investigated over a period of time (4 weeks). The O/W emulsion proves to be well stable even after 4 weeks, with a water separation rate of 0%.