Supercritical-Fluid Processing as A Thermodynamically Tunable Platform for Circular Manufacturing of Biomass-Derived Cosmetic Actives

The transition toward sustainable cosmetic manufacturing requires processing technologies capable of converting heterogeneous biomass resources into compositionally consistent, high-value functional ingredients. Supercritical-fluid (SCF) processing offers a uniquely tunable separation environment in which solvent density, selectivity, and mass-transfer characteristics can be continuously controlled through pressure–temperature manipulation. Unlike conventional extraction methods governed by fixed solvent chemistry, SCF systems enable phase-behavior–driven fractionation that allows targeted recovery of molecular families while preserving thermally sensitive bioactives. This review examines SCF processing as an engineering platform for translating agro-industrial residues into reproducible cosmetic actives within circular manufacturing frameworks. In this context, circular manufacturing denotes the upcycling of biomass residues into high-value cosmetic constituents via resource-efficient processing, solvent recovery, and waste mitigation, consequently optimizing material longevity and curbing environmental degradation. Emphasis is placed on the relationships between process parameters, extract composition, and functional performance relevant to formulation applications, including oxidative stability, lipid compatibility, and sensory attributes. The role of programmable fractionation, mild thermal environments, and closed-loop solvent operation in enabling cleaner and resource-efficient production is discussed alongside scale-up, process design, and techno-economic considerations. Recent developments in predictive modelling, process automation, and hybrid separation schemes indicate a gradual shift in SCF operation from empirical optimization toward model-guided process design. Rather than being treated as a purely extraction step, SCF systems are increasingly evaluated in terms of how thermodynamic control influences downstream material functionality. This perspective strengthens the role of SCF processing in connecting biomass valorization with the formulation requirements of sustainable cosmetic products.