A novel subcritical fucoxanthin extraction with a biorefinery approach.

• SFE was performed to extract fucoxanthin from Phaeodactylum tricornutum. • Extraction was conducted directly from wet microalga to reduce energy and cost. • A solvent-to-solid ratio of 200:1, 20 MPa, 35 °C at 120 rpm 60 min yielded 0.69 mg/g. • Residual biomass was characterized using light microscopy and SEM-EDS analysis. • Residual cells could be potential candidate for different commercial applications. Eco-friendly, cost efficient and effective extraction methods have become significant for the industries applying zero waste principles. The two main objectives of this study were; to examine fucoxanthin extraction from wet Phaeodactylum tricornutum using subcritical fluid extraction and to characterize the residual biomass in order to determine the potential application areas. The highest fucoxanthin yield of 0.69 ± 0.05 mg/g wet cell weight was achieved using methanol with solvent-to-solid ratio of 200:1 at 120 rpm, 20 MPa pressure and at 35 °C for 60 min by subcritical extraction. Microscopy images showed that most of the cells were disrupted and intracellular components were effectively released. Based on the results of energy dispersive spectroscopy, biomass contained a mixture of organic molecules including mainly carbon (57–72%), oxygen (26–41%), magnesium (0.6–1.4%) and silica (0.4–1%) (wt%). These results make the residual biomass a potential candidate for various areas such as bioenergy, material sciences and sensor technologies. [ABSTRACT FROM AUTHOR]