Supercritical CO2 Extraction of γ-Linolenic Acid from Spirulina platensis
Arthrospira (Spirulina) platensis contains large quantities of γ-linolenic acid (GLA). GLA is an essential omega-6 unsaturated fatty acid made in the human body from linoleic acid. It can be metabolized to various important eicosanoids such as prostaglandins, thromboxanes, leukotrienes, prostacyclins, and lipoxins. The aim of this study was to investigate the optimal extraction parameters of GLA from A. platensis using supercritical CO2 technology. Results showed that operating temperatures and pressures were important factors in the extraction of GLA. A maximum GLA yield of 161.98 μg/g could be obtained at a pressure of 30 MPa, a temperature of 60°C, and a CO2 flow rate of 6 mL/min. Conversely, only a yield of 104.16 μg/g could be obtained at a pressure of 10 MPa, a temperature of 40°C, and a CO2 flow rate of 6 mL/min. The correlation between pressure and yield could be explained by an increase in collision rates between CO2 molecules and carrier affinity under a high pressure. Therefore, an operating temperature between 50 and 60°C and a pressure of 30 MPa should be used to maximize the yield of GLA from A. platensis using supercritical CO2 technology.