Supercritical fluid carbon dioxide extraction (SFE-CO2)

SFE-CO₂ was performed on Super Critical Extraction system MV-10 ASCFE which consists of thermocube chiller, fluid delivery module (co-solvent pump and CO₂ pump), extraction oven (extraction vessels), automatic backpressure regulator (ABPR) and fraction collection module with makeup pump by Waters (Dublin, Ireland). 3 g of powdered sample was placed into a 3 ml sample vessel and extracted under the following parameters: CO₂ flow rate at 10 ml min⁻¹, ethanol co-solvent flow rate at 0.05 ml min⁻¹, and make-up solvent flow rate was 0.6 ml min⁻¹. All flow rates were kept constant throughout the process. A three factors, four levels orthogonal array design of L₁₆ (4³)²⁹ was employed for the optimisation of extraction parameters, temperature (∘C), pressure (bar), dynamic time (min) (Table ​(Table1).1). Sixteen experiments were performed in order to identify the best parameters for the extraction of polyprenol from selected plant species (Supplementary Table ^S1).

The parameters factors and levels of the orthogonal array design L₁₆.

Further optimisation experiments were carried out to investigate the effect of the extended dynamic time. These extractions were conducted with dynamic time of up to 7 h. The temperature and pressure selections for these further time experiments were 200 bar and 70 ∘C. Those temperature and pressure set-points were selected based on the initial development process being the best parameters which resulted in the highest polyprenol yield.