| In the application of cosmetics,chemical synthetic emulsifiers are prone to irritate the human skin and seriously affect the user experience.In response to this problem,8natural emulsifiers suitable for cosmetic preparation were screened out,and the emulsification performance of the emulsifier was determined by temperature resistance,cold resistance and centrifugal test.The interfacial tension,particle size distribution,interfacial shear viscosity and rheological behavior of the emulsion were measured,the optimal stability conditions were explored and the stability mechanism of the emulsion was analyzed.Experimental results show that wheat germ and lecithin have better emulsification stability in eight natural emulsifiers.The best solution for the preparation of wheat germ emulsion is emulsifier content 3%(w/w),oil-water ratio 3?7,homogenization time 18min,homogenization speed 1700 r/min.The best method for preparing emulsion with lecithin is emulsifier content 0.4%(w/w),oil-water ratio 2?8,homogenization time 17min,homogenization speed 1700 r/min.The measurement results of the morphology characteristics of the emulsion droplets show that with the increase of the emulsifier content,the particle size of the emulsion droplets is smaller and closely packed.In the 3~#emulsion with an emulsifier content of 3%,the particle size of the droplet with the highest volume fraction was 0.45?m.In the 8~#emulsion with an emulsifier content of 0.4%,the particle size of the droplet with the highest volume fraction was 0.36?m.The critical micelle concentrations of wheat germ and lecithin were 3.35%and 0.48%,respectively.When the emulsifier content is low,the viscosity modulus of the emulsion is dominant,and when the emulsifier content is high,the elastic modulus is dominant.The moisturizing effect of the cosmetic emulsion was measured,and the results show that the wheat germ and lecithin cosmetic emulsion can maintain the moisturizing effect for about 8 hours. |
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