## 1 Introduction
This dual organization lies behind its ability to stabilize a wide range of oil types and concentrations. Lamellar structures around oil droplets help to prevent coalescence and viscoelastic lamellar gel imparts suspending properties. Moreover, some water can be partially fixed inside the gel network, between the lamellae, supported by hydrogen bonds [14; 15]. The \"entrapped water\", acting as a water reservoir, was assumed to play a role in skin hydration. In vivo moisturizing effects of simple placebo emulsions containing 5% and 7% emulsifier, combined with 17% and 20% embilient, respectively, were confirmed using corneometry and measurements of transepidermal water loss (TEWL) [16; 17]. Significant effects were described 15 min [16] and 60 min [17] after a single application on the forearm. The contribution of C16-C18 APG in skin moisturizing was also reported in the presence of various active ingredients, when used as a single emulsifier, and when coupled with a similar glucolipid structure based on a C20-C22 fatty chain [18; 19]. Glucolipid emulsifier based on wide fat cuts, from medium C12 chains to long C22 chains (i.e., INCI: C14-C22 alcohols (and) C12-C20 alkyl glucoside) is less known and poorly documented in the literature. Its main specificity lies in obtaining stable sprayable to thick textures depending on the emulsion composition, associated with a characteristic light skin feel, very different from the C16-C18 variant [20]. Varying the texture and consistency allows multiple applications, on the whole body, small and large areas, including the face and difficult to reach areas such as those with hair. One publication reported the use of C12-C20 glucolipid emulsifier (at 2%) in combination with short cut C20-C22 glucolipid emulsifier (at 8%) to formulate stable emulsions with up to 10% glycolic acid [21]. Microscopic observation of the placebo with polarized light revealed lamellar phases formed by the emulsifying system surrounding oil droplets. A short-term moisturizing effect using assessment of transepidermal water loss (TEWL) was also visualized 30 min and 1 h after application of the placebo cream. The absence of irritation in human studies with 10% glycolic acid led to the assumption that the vehicle based on these emulsifying combinations could contribute to reducing the undesirable effects of glycolic acid. A second paper [22] displayed formulations combining the C12-C20 glucolipid emulsifier (at 2%) and other APGs from C16-C18 or C12-C18 (at 4%) to stabilize mineral waters (thermal spring waters). Significant moisturizing properties were reported using in vivo comeometry measurements 1 h and 24 h after application, for all formulations. Mineral waters enhanced the moisturizing effect compared to the placebo. In both cases, the C12-C20 glucolipid emulsifier was not used alone. Moreover, the studies reporting moisturizing effects were conducted in the same European country. Therefore, this work aimed to investigate the immediate moisturizing effect of four minimalist O/W emulsion structures, using C12-C20 glucolipid emulsifier alone at a realistic dosage of 3%, on various skin types subjected to different climates and environments on a daily basis. The C12-C20 glucolipid emulsifier was selected for its light skin feel, suitable for warm climates. The emulsion structures reflected the formulation habits in different geographical locations. The formulations had different dosages and nature of oils to meet local consumers' sensorial expectations and contained a stabilizing rheology modifier at the concentration required for stability. As the selection of oily phase was supposed to have an influence on the result, high concentrations of the oily phase and oils with long fatty chains were hypothesized to be the most favorable conditions for achieving a moisturizing effect. Experiments were conducted in four locations: Brazil, France, India and Mauritius.