Fractionation of lipophilic compounds of Tagetes patula flowers by using consecutive 2-step extraction with different CO2 densities

Abstract

Distillation has been widely applied for the recovery of Tagetes patula L. essential oil, while fractional supercritical fluid extraction of this plant with carbon dioxide (SFE-CO₂) remains underexplored and data on the volatiles and phytochemicals in CO₂ extracts have not been reported. This study investigated the fractionation of T. patula flowers using supercritical CO₂, with initial extraction at lower pressure (10 MPa, 40°C; SFE-CO₂-I) followed by further extraction at higher pressure (45 MPa, 50°C; SFE-CO₂-II). Essential oil obtained by hydro-distillation contained the most volatiles, followed by SFE-CO₂-I, while SFE-CO₂-II was a poor volatile source. Higher pressure yielded 1.25–2.9 times less phytosterols, tocopherols, and unsaturated fatty acids compared to lower pressure, but was more effective for plant pigment (chlorophylls, carotenoids) extraction. The results demonstrate that different lipophilic compound classes in T. patula flowers can be selectively concentrated at varying pressures, highlighting the potential of SFE-CO₂ fractionation.