Selective supercritical fluid extraction (SFE) coupled to impregnation of solid matrix for the cosmetic formulation

Supercritical Fluid Extraction (SFE) presents several advantages in comparison to other extraction methods. First, the extraction is dynamically performed with the fluid going continuously through the cell, which favors the mass transfer from matrix to fluid. Secondly, the addition of a modifier having varied polarity, combined to temperature and backpressure changes improves the selectivity of the extraction. Many seeds contain mainly lipids and only small amounts of bioactive compounds. The extraction of enriched fractions of these bioactive compounds, meaning with low lipid contents, is a real challenge. Selective extraction of some bioactive compounds by SFE was studied. Different extractions were achieved depending on the type of modifier (ethanol or ethanol/water), its percentage (5 and 30%), the temperature (from 30 to 60 °C) and the backpressure (10 and 20 MPa). For each extract, the analyses of both the composition of triglycerides and bioactive compounds were performed by SFC/UV. The yield (based on the mass) and an enrichment factor (based on relative areas of peaks) were calculated for each extraction condition. Results show that the increase in the polar modifier (ethanol) up to 30% favors the extraction selectivity, thereby reducing the amount of non-polar triglycerides extracted, and increasing the concentration of the target compounds. However, for providing an active ingredient for the cosmetic field, an additional step of deposing the bioactive compounds onto a solid porous support was coupled on-line to the selective extraction step. In that case, the modifier content should be lower to favor the trapping of compounds, and an ethanol/water mixture with a higher polarity is preferred. The influence of the trapping conditions was also studied, e.g., the weight ratio of seed/solid support, the impregnation cell temperature and the pressure drop between the extraction and the trapping steps.

Keywords: SFE, supercritical impregnation, bioactive compounds, cosmetic ingredient.