A Novel Quality Control Method for the Determination of the Refractive Index of Oil-in-Water Creams and Its Correlation with Skin Hydration

Abstract

The sensory properties of cosmetic products can influence consumers’ choice. The accurate correlation of sensory properties, such as skin hydration, with the material properties of the formulation could be desirable. In this study, we aimed to demonstrate a new method for the in vitro measurement of the refractive indices (RIs) of turbid creams. The critical wavelength of each cream was obtained through direct measurement using a sun protection factor (SPF) meter; the wavelength value was then applied in the Sellmeier equation to determine the RI. The results obtained from the in vitro skin hydration measurement for each cream correlated with their RI values. This suggests that RI measurements could be a useful predictive tool for the ranking of creams in terms of their skin hydration effects.

Impact of incorporating sesame oil (Sesamum indicum L.) in an Algerian frying oil and margarine formulation

“…The refractive index (RI) is a measure used for identification and as a criterion of purity of oils. It is also used as an index of the degree of hydrogenation of the oil 32,33 . The RI of oils depends on their molecular weight, their degree of unsaturation, the chain length of fatty acids, and the degree of conjugation 34 .…”

Special Issue “Current and Evolving Practices in the Quality Control of Cosmetics”

“…To enable time-and cost-effective quality control testing, assessment methodologies are constantly evolving. In the study conducted by my research group [7] we reported a novel QC method for the determination of refractive indices of creams, using an SPF meter. The RI values then presented the correlation with preliminary skin hydration data after the application of the creams.…”