Anticipating cosmetic emulsion stability using a novel multi-analytical approach

The physicochemical stability of cosmetic emulsions is crucial for successful commercialization and consumer satisfaction. This study presents an innovative protocol that combines rheology, turbidimetry and granulometry to predict emulsion stability more efficiently.

Industrial emulsions, including some commercial products, were selected to compare stable and unstable samples with minimal formulation differences. Granulometry, turbidimetry and rheology assessments were used to evaluate physical and structural properties. The collected data were subjected to advanced statistical analysis using experimental design methods.

Granulometry, turbidimetry and rheology each effectively distinguished stable from unstable emulsions. Stable emulsions maintained a constant median particle size, while unstable samples exhibited significant increases. Viscosity changes were observed only in unstable emulsions. Turbidimetry showed a Turbiscan Stability Index (TSI) >3 for unstable emulsions and <3 for stable ones. Notably, this combined protocol identified instability as early as 8 days-much faster than standard ISO methods, which require up to 30 days.

Integrating granulometry, turbidimetry and rheology with advanced data analysis enables a rapid, reliable and sensitive prediction of cosmetic emulsion stability. This approach overcomes the limitations of traditional testing by allowing earlier detection of instability, improving formulation development, quality control and time-to-market. Future work will assess the protocol's applicability to a wider range of emulsion types.