Supercritical CO2 extraction of linseed: Optimization by experimental design with regards to oil yield and composition

Abstract

The aim of the present study is to evaluate the effect of CO2 pressure, temperature, and CO2 flow rate on supercritical fluid extraction of linseed oil using neat CO2. Chosen methodology is based on central composite rotatable design, responses studied are extract yield, oil yield, water‐extract ratio, oil γ‐tocopherol content, oil polyphenols content, alpha linolenic acid proportion in oil, and oil acid value. Acid value, tocopherol content, and linolenic acid proportion are independent responses of studied factors. On other responses, only pressure and temperature have an influence. Based on response surface analysis and multiresponses optimization, optimal conditions for oil yield, and oil polyphenol content maximization and water‐extract minimization were determined (42.5 MPa, 120°C, 12.5 kg/h [125 g/g solvent:feed ratio]). Optimal conditions were tested and validated on three linseed varieties. A maximal oil yield of ≈60% was reached containing up to 100 mg FAE/kg oil.Practical applications: Results of this study can be applied for developing a new linseed oil extraction process based on supercritical fluid extraction without co‐solvent addition. The optimized process permits an increased extraction of antioxidants. Extraction of antioxidants such as γ‐tocopherol or polyphenols could provide a protection of oil against oxidation. This protection is of great interest for sensitive oils such as the highly polyunsaturated linseed oil. Application to other oleaginous seeds is also possible.Supercritical CO2 extraction of linseed oil is optimized through design of experiment with regards to oil yield and oil quality. Optimization enable to identify conditions (42.5 MPa, 120°C) that favors oil yield (≈60%) while enhancing oil polyphenols content (50–100 mg FAE/kg). Extraction performances are variety dependent.