The role of rheology in cosmetics research: a review

Since the dawn of human civilization, cosmetics have been an important part of life for various reasons, including aesthetic purposes, skin protection, and representing social status and ideology for social and political reasons. Nowadays, due to advances in science and technology, cosmetics comes in countless distinctive formulations, each tailored to specific purposes and preferences. Rheology has been an essential tool in designing and analyzing complex cosmetic formulations, because of inherent characteristics of their usage, which inevitably involves processes of flow and deformation. Typically, the sensory texture of cosmetic formulations has been correlated with rheological measurements. Furthermore, because the physical and chemical properties, as well as the microstructural status of cosmetic formulations, are well reflected in their rheological behavior, rheology has proven to be an effective metric for assessing stability. This review aims to provide a structured overview of how rheology has been utilized in the cosmetics field and highlight its advancements. We specifically focus on the role of rheology in analyzing the sensory texture and stability in cosmetic formulations, emphasizing a variety of previous studies. In the last part, we present latest applications of rheological analysis combined with other modern techniques, including artificial intelligence and eco-friendly technologies.