Continuous extraction of lipids from Schizochytrium sp. by CO2-expanded ethanol

•CO2-expanded ethanol (CXE) is a promising solvent for lipid extraction.•Continuous CXE extraction can be operated at low pressures and temperatures.•CXE provides an extracted lipid yield of 87 wt% within only 30 min.•CXE is superior to ethanol and pressurized ethanol for extraction.•The advantages of using CXE include less amount of ethanol and less time required.

CO2-expanded ethanol (CXE) was used to extract DHA-containing lipids from Schizochytrium sp. with a 35.7 wt% lipid content of dry biomass in a continuous mode. The effects of operation variables such as temperature, pressure, ethanol flow rate and CO2 flow rate on extraction performance were investigated. Based on a 24-central composite design and response surface methodology, the optimal operating conditions were determined to be a pressure of 6.9 MPa, a temperature of 313 K, an ethanol flow rate of 1 mL/min and a CO2 flow rate of 6.0 mL/min, providing an extracted lipid yield of 87 wt% over an extraction period of 30 min. Not only the lipid yield obtained using CXE was observed to be significantly greater than those using ethanol and pressurized ethanol as the solvents, but also a lower amount of ethanol and less time were required to achieve the same extraction yield by using CXE.