Enhanced extraction of flaxseed oil, tocopherols, and fatty acids using supercritical carbon dioxide with ethanol: Process optimization and modelling

Abstract

This study explores the extraction of flaxseed oil using supercritical CO₂ (SC-CO₂) with ethanol as a co-solvent, optimizing key process parameters to enhance oil yield and total tocopherol content (TTC). The influence of pressure (20–30 MPa), temperature (40–60°C), and CO₂ flow rate (2–6 mL/min) was analyzed using response surface methodology (RSM). The optimal conditions (20 MPa, 51°C, 2 mL/min) yielded 36.86% oil and 112.71 ppm tocopherols, demonstrating the effectiveness of SC-CO₂ extraction. The addition of ethanol improved tocopherol and monounsaturated fatty acid (MUFA) recovery, while extraction without ethanol favoured polyunsaturated fatty acid (PUFA) retention. Gas chromatographic analysis confirmed that SC-CO₂ extraction produced a superior fatty acid profile compared to Soxhlet extraction, preserving higher levels of α-linolenic acid (ALA) and oleic acid. Solubility studies indicated that moderate pressure and temperature conditions enhance oil recovery. SC-CO₂ with ethanol proved to be an efficient and environmentally friendly alternative to conventional extraction methods, producing high-quality flaxseed oil rich in bioactive compounds. These findings support the scalability of SC-CO₂ extraction for nutraceutical, pharmaceutical, and food applications. Future research should explore antioxidant stability and large-scale processing feasibility to enhance industrial adoption.