Supercritical carbon dioxide extraction of Solidago gigantea Ait.: Optimization at quarter-technical scale and scale up the process to half-technical plant

Solidago gigantea Ait. (goldenrod) is widely spread in Poland and has a traditional usage as medicinal plant due to the content of bioactive compounds. The main aims of this research were to obtain the optimal conditions of supercritical fluid extraction (SFE) of S. gigantea with carbon dioxide as a solvent in the quarter-technical plant and to scale-up the process to half-technical, where both works in a high range of pressure - up to 100 MPa. Response surface methodology (RSM) was used to analyze and evaluate the influence of process parameters: pressure (P, MPa), temperature (T, K) and solvent flow rate (F, kg h(-1)) on output variables. The selected output variables were yield, total phenolics content, total chlorophylls content and lipids content. The optimal parameters obtained at quarter-technical plant, for a chosen response - yield, were: T = 353.15 K (80 degrees C), P = 72.31 MPa and F = 6.97 kg h(-1). Scale-up extractions were conducted according to various criteria at half-technical plant under optimal conditions. Extraction with simultaneously constant ratio of the solvent flow rate to the mass of the feedstock (Q CO2/M, kg h(-1) kg(-1)) and a constant ratio of solvent mass to mass of the batch (S CO2/M, kg kg(-1)) ended with the best results: mass of obtained extract was 0.311 kg (7.17% DM - dry matter). Analysis of biological properties of the obtained product showed that it exhibits antibacterial activity and very low level of cytotoxicity and therefore, it can be safely used in pharmaceutical and cosmetics formulations.