Conception de capsules naturelles innovantes et compréhension des intéractions au sein de matrices cosmétiques (Caps4Skin)

Antioxidants play a key role in cosmetic formulations, whether to stabilize products or for their skin benefits. However, their incorporation remains a challenge due to their low solubility and sensitivity, which can lead to premature degradation of formulations and even pose risks to consumers. Encapsulation offers a promising solution to improve their solubility, stability, and enable controlled release. This thesis project aims to develop active and innovative microcapsules based on natural ingredients for cosmetic applications. Two main objectives were explored: developing reliable encapsulation methods and analyzing the behavior of microcapsules in natural cosmetic matrices, mainly emulsions. Two encapsulation techniques were studied: spray-drying for ascorbic acid encapsulation and complex coacervation for α-tocopherol. It was demonstrated that the biopolymer-active ratio during spray-drying significantly influences the morphology of the microcapsules, enhancing their encapsulation efficiency and the protection of the active ingredient under extreme storage conditions. Integrated into emulsions or gels, these microcapsules impacted the texture properties, particularly spreadability. Furthermore, the combination of fungal chitosan and gum Arabic through complex coacervation allowed the effective encapsulation of α-tocopherol, with improved stability, especially after the addition of tannic acid as a cross-linking agent. Finally, these stable and robust microcapsules had a notable impact on the structure, texture, and rheological properties of the formulations. The practical outcomes of this study are significant for various sectors, particularly the cosmetic industry. The development of stable and multifunctional microcapsules presents promising opportunities for the formulation of innovative products with enhanced textural properties, while ensuring effective protection of the encapsulated actives. This could enhance the stability and performance of products, thereby improving their durability and effectiveness.