High-yield dimethyl ether-based recovery of astaxanthin and fatty acids directly from wet Haematococcus pluvialis

Efficient and eco-friendly methods for extracting bioactive molecules are crucial for achieving economically viable microalgae biorefinery. In this study, high-value-added intracellular bioactive compounds were efficiently recovered directly from the red cysts of wet Haematococcus pluvialis. An integrated processes involving liquid dimethyl ether (l-DME) extraction at 45 °C and 2 MPa for 90 min and subsequent dimethyl sulfoxide (DMSO) extraction at 65 °C for 5 min enabled almost complete recovery of astaxanthin (99.6%) and total fatty acids (99.8%) from wet H. pluvialis cyst cells. Notably, this green and sustainable strategy did not involve high-cost and energy-intensive drying, or cell wall-disruption steps. l-DME extraction produced a solvent-free, dry extract with high astaxanthin (43.9 mg g⁻¹ dry extract) and essential fatty acids (ω3, ω6, and ω9; 290.1 mg g⁻¹ dry extract) contents; whereas the astaxanthin and fatty acid contents of the DMSO extract produced from raw H. pluvialis cyst cells (freeze-dried and ball-milled at 200 rpm for 30 min) were 1.5- and 1.7-fold lower, respectively. The dry extract also exhibited 1.6-fold greater antioxidant activity than the DMSO extract, thereby indicating its potential for direct application in nutraceutical, pharmaceutical, and cosmeceutical formulations with high bioactivity and safety.