Brazilian and French sensory perception of complex cosmetic formulations: a cross-cultural study

Talk to us about your skin: The relationship between spoken language and haptic exploratory procedures

OBJECTIVE

To enhance satisfaction, the cosmetics industry needs to clearly understand consumers' descriptions of their key tactile preferences. It is difficult for researchers to understand verbal descriptions from people whose native language is different from their own. Previous research has implied that some sensory words with the same lexical meanings have been observed in different haptic exploratory procedures (HEPs). Therefore, our study aims to investigate and understand the key tactile perceptions of people from five different countries based on their descriptions and their HEPs.

METHODS

In Experiment 1, 1545 participants living in the US, Japan, China, Italy, and Thailand described their major tactile perceptions as efficacy in skincare, and we analysed the frequency of each word used in their answers. In Experiment 2, we confirmed the task to observe HEPs for Chinese, Italian, and Thai participants. A total of 24 participants in China, 33 participants in Italy, and 30 participants in Thailand freely explored their faces with their hands and answered which side more closely matched the major tactile adjectives. Experts classified the observed HEPs into six classifications within two categories and three contact area sizes and investigated the cultural differences.

RESULTS

More than 2% of the Chinese, Italian, Thai, US, and Japanese participants described 33, 20, 29, 22, and 18 words, respectively, as efficacy in skincare. Verified words that described the major tactile perceptions in each native language had the same meanings as moistness, firmness, softness, smoothness, and so on. We could confirm the HEPs of these major feelings for the participants from each culture. Chinese and Thai participants' HEPs for moistness or softness were observed with a pressing movement. Conversely, Italian participants' HEPs for moistness or softness were observed with a rubbing movement.

CONCLUSION

This study showed that words with the same lexical meanings evoked different HEPs. The results imply that different HEPs can provide different physical stimuli on the skin. Therefore, it is important to survey both objects and HEPs to better understand the tactile experience.

Film-Forming, Moisturizing, and Sensory Properties of a Cosmetic Formulation Containing Tara Gum and Brazilian Berry Extracts

The development of cosmetic formulations with moisturizing and film-forming properties has been very important to help keep skin physiology and protection. In this context, this study aimed to develop a cosmetic formulation containing Tara gum and Brazilian berry extract and evaluate its physical-mechanical, film-forming, and sensory properties. A gel formulation was developed based on Tara gum added to Plinia cauliflora extract and was characterized by its spreadability profile and sensory properties. A clinical study was carried out with ten participants to evaluate the skin microrelief, stratum corneum water content, transepidermal water loss (TEWL), and skin morphological characteristics by reflectance confocal microscopy (RCM) before and after 2 h of application of the formulations. The formulation with Brazilian berry significantly decreased the work of shear parameter, which can be correlated with improved spreadability in the sensory analysis. The clinical study showed that both formulations improved skin hydration and reduced the TEWL. The RCM imaging analysis showed the visible film on the skin surface, a decrease in the size of furrows, an increase in the reflectance of the interkeratinocytes, and reflectance of the stratum corneum for both formulations. These results were more pronounced for the formulation containing Brazilian berry. The Tara gum in the gel formulation promoted the formation and visualization of a polymeric net on the stratum corneum surface, demonstrated by the images obtained from RCM. However, the formulation added with the Brazilian berry extract improved the skin microrelief, honeycomb pattern of the epidermis, and skin hydration in deeper layers of the epidermis.

Efficient Development of Green Emulsifier/Emollient-Based Emulsion Vehicles: From RSM Optimal Experimental Design to Abridged In Vivo Assessment

Since natural-origin, sustainable ingredients are preferred by modern consumers, novel emulsifiers and emollients keep entering the market. This study hypothesizes that a combination of in silico, instrumental tools and simplified sensory studies could be used to efficiently characterize emulsions in a shorter timeframe. A total of 22 rather simple o/w emulsions were prepared by a time/energy-saving emulsification process. A natural mixed emulsifier (Lauryl Glucoside/Myristyl Glucoside/Polyglyceryl-6 Laurate) and two emollients (both with INCI name C15-19 Alkane) were used. The performed D-optimal experimental design within the response surface method (RSM) significantly narrowed down the number of samples about to enter the stage of texture, friction and sensory studies to the samples comprising 30% of a respective Emogreen emollient and 2% or 3% of the emulsifier. The sample comprising 2% emulsifier/30% Emogreen^® L15 showed significantly higher firmness (42.12 mN) when compared to the one with 2% emulsifier/30% Emogreen^® L19 (33.62 mN), which was somewhat unexpected considering the emollients' inherent viscosity values (4.5 mPa·s for L15 and 9 mPa·s for L19). The sample with 2% emulsifier/30% Emogreen^® L19 managed to maintain the lowest friction, while the one with 3% emulsifier/30% Emogreen^® L19 released its full lubricating potential in the second part of the measurement (30-60 s). The obtained results revealed the strengths and weaknesses of each formulation, narrowing down their possible applications in the early development stage.

Skin Sensory Assessors Highly Agree on the Appraisal of Skin Smoothness and Elasticity but Fairly on Softness and Moisturization

We tested the reliability of sensory evaluations of tactile sensation on bare skin and investigated the reliability among evaluation attributes by trained and untrained assessors. Two trained professional panelists and two untrained researchers evaluated skin in terms of several attributes: smooth–rough, elastic–not elastic, soft–hard (surface), soft–hard (base), moisturized–dry. Twenty-two women aged 25–57 years were evaluated, and the sensory evaluation was repeated twice. Correlation coefficients and intraclass correlation coefficients (ICCs) were used to examine intra- and inter-assessor reliability. The sensory evaluation and physical quantities acquired by commercial and non-commercial instruments were moderately correlated. Smooth–rough and elastic–not elastic showed high or moderate inter-assessor reliabilities with mean correlation coefficients between panelists of 0.81 and 0.58, respectively. Further, the ICC (2,1) values were 0.64 and 0.51, respectively, and the ICC (2,2) values were 0.77 and 0.67, respectively. Conversely, the reliabilities of soft–hard (surface), soft–hard (base), and moisturized–dry were low; the mean correlation coefficients between the panelists were 0.36, 0.23, and 0.22; the ICC (2,1) values were 0.27, 0.23, and 0.17; and the ICC (2,2) values were 0.42, 0.29, and 0.26, respectively. Reliability differed between attributes. We found no meaningful differences between the trained and untrained panelists regarding intra- or inter-assessor reliability.