Instrumental and sensory methodologies to characterize the residual film of topical products applied to skin

Abstract

Background The work is aimed at the development of a methodology to characterize the tactile properties of topical products during application. Specific attention was paid to the study of the residual properties left at the surface of the skin. This approach was interestingly used to better understand the formulation factors governing the skinfeel of topical preparations. Materials and Methods Cosmetic and pharmaceutical topical products were selected based on their various texture, galenic form (gel or emulsion), and composition (polymer used as texturing agent). Key texture attributes namely Firmness, Stickiness, Spreadability, and Amount of residue were objectively evaluated using sensory analysis. Additionally, texture analysis (compression test), rheology (flow test), and tribology (in vivo friction test) were carried out. Results Sensory evaluations highlighted a great diversity of tactile properties among products when applied to skin. For example, assessors perceived an important amount of residue left by emulsions whereas gels were not leaving any residue after application to the skin. These results were confirmed by in vivo tactile friction measurements with two distinct evolutions in time of the residual film properties. Conclusion The present investigation shows how the tactile properties of topical gels and emulsions are studied using complementary tests in order to understand and improve the skinfeel of topical preparations.

Sensory perception of textural properties of cosmetic Pickering emulsions

“…2). The important SD for the obtained results is usual for the sensory analysis inherent to differences in assessors evaluation [26][27][28][29]. Despite the identic water quantity in all the samples, the panel could statistically discriminate the products.…”

“…The sensory analysis is essential when developing products with further applicative interest. It was largely described for cosmetic raw materials and emulsions , but only a few results were given for Pickering emulsions. Marto et al .…”

“…The sensory analysis is essential when developing products with further applicative interest. It was largely described for cosmetic raw materials and emulsions [24][25][26][27][28][29], but only a few results were given for Pickering emulsions. Marto et al [4] evaluated the textural properties of the Starch-based emulsions using a simple sensory questionnaire in which the basic characteristics, that is texture and skin feel, were evaluated by the volunteers.…”

Comparison of two skin temperature assessment methods after the application of topical revulsive products: Conductive iButton data logger system vs contact‐free infrared thermometry

“…[1][2][3][4] The measurement is challenging even more when sweat or topical products cover the skin surface. [5][6][7] The ingredients of plant-derived revulsive products may induce changes in skin blood flow, affecting skin temperature. [8][9][10][11] To the best of authors' knowledge, to date, no study has compared conductive and contact-free skin temperature measurement methods to perform a continuous observation of the physiological changes induced by revulsive products.…”

“…Skin temperature measurement techniques comprise conductive thermocouples, thermistors and telemetry systems as well as contact‐free infrared thermometry and imaging 1‐4 . The measurement is challenging even more when sweat or topical products cover the skin surface 5‐7 . The ingredients of plant‐derived revulsive products may induce changes in skin blood flow, affecting skin temperature 8‐11 .…”