Effect of xanthan gum on stability and rheological behavior of O/W emulsion

Oil-in-water emulsions were prepared by homogeneous emulsification using glycerol stearate (and) PEG-100 stearate (A165) as emulsifier and xanthan gum (XG) as thickener. The effects of oil and XG content on the stability and flow behavior of emulsion were studied by polarizing microscope and rheometer. The hydrogen bonding interaction between xanthan gum molecules was studied by molecular dynamics simulation, and then the interaction between xanthan gum and emulsifier was further studied. The results showed that when there is no xanthan gum and the emulsifier content is 3%, the oil content increased, the particle size decreased. When the oil content is constant, the emulsion particle size decreases at first and then increases with the XG content increasing, which is due to the accumulation of XG and emulsifier on the oil-water interface, and the interfacial film thickens. The flow behavior of O/W emulsion can be described by a power law function. The emulsion without XG is Newtonian fluid at low oil content, and when the oil content increased, it was transformed into non-Newtonian fluid. The viscosity and consistency index increased with the increase of XG, which is due to the hydrogen bond between XG and emulsifier. However, the flow behavior index decreased greatly, the degree of shear thinning of emulsion enhanced. XG increased the viscosity of the mobile phase, under shear force, the deformation degree of droplets and the degree of shear thinning were different. This study can provide a reference for further regulating the stability and flow characteristics of skin care emulsion.