Extraction of Bioactive Compounds Using Supercritical Carbon Dioxide

Microalgae Dunaliella salina contains useful molecules such as -carotene and fatty acids (FAs), which are considered high value-added compounds. To extract these molecules, supercritical carbon dioxide was used at different operative conditions. The effects of mechanical pre-treatment (grinding speed at 0-600 rpm; pre-treatment time of 2.5-7.5 min) and operating parameters for extraction, such as biomass loading (2.45 and 7.53 g), pressure (100-550 bars), temperature (50-75 degrees C) and CO2 flow rate (7.24 and 14.48 g/min) by varying the extraction times (30-110 min) were evaluated. Results showed that the maximum cumulative recovery (25.48%) of -carotene was achieved at 400 bars and 65 degrees C with a CO2 flow rate of 14.48 g/min, while the highest purity for stage (55.40%) was attained at 550 bars and 65 degrees C with a CO2 flow rate of 14.48 g/min. The maximum recovery of FAs, equal to 8.47 mg/g, was achieved at 550 bars and 75 degrees C with a CO2 flow rate of 14.48 g/min. Moreover, the lowest biomass loading (2.45 g) and the first extraction cycle (30 min) allowed the maximum extraction of -carotene and FAs.