## 4 Discussion  
The research intended to investigate if C12-C20 glucolipid emulsifier, used as the sole emulsifier at a realistic dosage of 3%, would allow flexibility in the formulation of moisturizing emulsions across different geographies or if the desired moisturizing effect would be strongly dependent on the embilient composition and/or user skin type and climatic conditions. Investigations were conducted on O/W emulsions with a reduced number of ingredients for an easier understanding of their contribution. Apart from this technical consideration, \"minimalist formulation\" is a topical subject, reported as a consumer-requested solution for a more sustainable approach and communication transparency [29]. Digitally connected consumers are keen to know more about the ingredients and their role in the formulation. At the same time, a great deal of research is being conducted on consumer motivations for a more sustainable consumption [30]. Shrinking the ingredient list is one way to reduce dependency on materials [29]. An analysis of personal care products launched on the market reflects the development of that trend: the number of products that include the word \"minimalist\" or \"minimalism\" in their descriptions was multiplied by six between 2017 and 2022, driven by the European and Asia-Pacific area [31]. In this context, interest in studying the efficacy of simple formulations has resurged, as formulation requirements have evolved compared to the literature. More inclusivity is expected. Lower doses have become the norm and represent a challenge to ensure stability, a positive sensory experience and efficacy. Pleasant skin feel and efficacy are linked for a positive consumer perception. A recent study performed on the forearm of thirty female volunteers showed that increase in stratum corneum hydration measured by skin capacitance enhanced the pleasantness rating when submitted to a gentle brushing movement [32]. But to be pleasant, skin feel should be appropriate to skin type and environmental conditions. Therefore, the ability of a modernized emulsion base to withstand changes in composition while keeping its targeted moisturization efficacy is of interest. Carrying out more inclusive tests was the first step to complete knowledge compared to the literature on APGs. One of the concerns for any formulator is whether one selected ingredient and the resulting formulation could have the same effect, moisturization in the present case, on very different users seeking the same skin benefit [33]. Variations in degree of skin moisturizing efficacy versus baseline, using corneumetric measurements, were pointed out in a multicentric study (349 volunteers in six centers in Germany, Switzerland and USA) one day after two applications of the same O/W emulsion base [28], despite a similar standardized protocol. In the current work, recruitment of volunteers with the full range of phototypes was firstly taken as a way to involve as diverse a panel of many users  
Figure 8: Changes in TEWL during the study carried out in Mauritius. Tewametry measurements (g/m\({}^{2}\)/h) at T0, 6 h and 24 h after a single application. Values are expressed as mean \(\pm\) SEM; ns: not significant; * \(p\) \(<\) 0.05, ** \(p\) \(<\) 0.01 vs. T0. as possible, based on their own perception of their skin [34]. For example, self-perception of facial aging of more than 3000 multinational women aged 18 to 75 years, collected by comparison with photonameric scales, was found to be correlated to phototypes. Women with phototypes V/VI and III/IV reported facial aging characteristics 10 to 20 years later than those with phototypes I/II. Most women reported using facial moisturizers: 63% among phototypes I/II to 39% among phototypes V/VI [35]. Secondly, the user's daily environment influences the state of their skin upon arrival and may contribute to the variation in individual responses when applying a cosmetic product [36]. Environmental factors are known to have a decisive influence on skin biophysical parameters [33; 37].