How does composition influence the texture of cosmetic emulsions?
Abstract
Using the Spectrum Descriptive Analysis method, the present work defines a methodology developed in order to discriminate and characterize cosmetic oil-in-water emulsions as well as their respective aqueous phases containing xanthan gum. The objective was to describe and understand how composition parameters govern texture perception, through the study of the impact of the amount of (1) xanthan and (2) oil phase. For that purpose, emulsions were developed by varying either their amount of xanthan or oil concentration. Seven texture attributes were selected and defined using precise and strict evaluation protocols and notation scales to set up a quantitative framework: integrity of shape, penetration force, wetness, ease of spreading, grease, stickiness and gloss. Results demonstrate the contribution of each parameter to the texture of emulsions and aqueous phases. For example, increasing the oil phase ratio in emulsion mainly enhances the consistency, grease degree and residual stickiness of the creams. Moreover, the study establishes consistent linear relationships according to the concentration in xanthan in solutions for five attributes: integrity of shape, penetration force, wetness, ease of spreading and gloss. Interestingly, the effect of xanthan in emulsions is similar but obviously diminished when compared to polymer solutions.