Design of natural origin foundations based on rheological studies to select raw materials, to optimize texture and to predict stability

Consumer awareness and market trends lead to the need of cosmetics as sustainable as possible. For this reason, it is essential to find equally performing natural or natural-origin alternatives to synthetic raw materials. Therefore this current, we developed a new foundation in an O/W emulsion type, starting from an existing one and increasing the respective Natural Origin Index (NOI), obtaining the equivalent cosmetic performances. The systematic use of rheology as the main characterization tool enabled the development of predictive structure/performance relationships, minimizing the adoption of trial and error formulation approach, saving time, predicting application properties, sensorial qualities and their stability. The work was carried out systematically in different steps, in order to introduce one variable at a time. Every step was focused on the replacement of one original raw material with the correspondent natural ingredient in order to have the same rheological behavior. We replaced the starting gelling system, emulsifiers, stabilizer and preservatives. Dealing with viscoelastic systems, it was possible to investigate the structure of the obtained samples with continuous and oscillatory rheology. During the whole experiment a Temperature Sweep analysis was carried out to have some preliminary stability information. An in-depth study of different natural gelling system was performed in aqueous solution. The substitution of the other ingredients was completed in white emulsions containing the optimized quantities and type of raw materials. Two foundations with higher NOI level were obtained by addition of pigments to the white formulas, containing respectively two different gelling system (xanthan gum and sclerotium gum). To evaluate the performance and sensory characteristics and to compare those with the original product we performed oscillatory measurements, Flow Ramp in controlled shear rate, Creep Recovery and Texture Analysis, to study information about spreadability, structural recovery and sensorial properties. In the end, a rheology study of the scale up of the formulas was carried out. Those measurements made possible to select a single formula(the one with sclerotium gum) with similar cosmetic characteristic with respect to the starting foundation. The systematic approach adopted led to two new foundations starting from an existing formula, with an increased NOI, higher than 81%. Rheology has uniquely determined the suitable raw materials for replacing non-natural ones, knowing their viscoelastic structural properties and their behavior as a function of quantities. Rheological studies also pointed to potentially unstable formulas, discarding some of those during the early stages of the study and finding a correlation with what happened in rheometry shortly after the formulation and after months in thermal stability. Following comparisons between the two final foundation by structure and texture analysis, thermal stability and scalability, it is possible to state that the one with sclerotium gum is more similar to the standard than the one with xanthan gum, even if both had higher NOI. Rheology acted as a predictive tool for the optimization of the formulation of a natural foundation stable over time and scalable.