Influence of extraction solvent system on extractability of lipid components from different microalgae species

The purpose of this work was to evaluate two food grade solvent systems, hexane/isopropanol (3:2; HI) and hexane (H), for the extraction of lipids from different omega-3 LC-PUFA rich microalgae: Isochrysis galbana, Nannochloropis gaditana, Nannochloropsis sp. and Phaeodactylum tricornutum. We not only focused on differences in lipid yield, but also lipid class, omega-3 LC-PUFA, carotenoid and sterol yields. Furthermore, an estimation of the feasibility of these microalgae oils as an alternative for fish oil was made. For all tested microalgae species, the highest food grade lipid, lipid class, omega-3 PUFA, carotenoid and sterol yield were obtained with HI, with a general recovery highest from Isochrysis, lowest from both Nannochloropsis species, and intermediate from Phaeodactylum. Total lipid recovery values between 14 and 76% depending on solvent and species were obtained. It was also shown that the omega-3 fatty acid content of all oils was quite similar, while only the H extract was enriched in neutral lipids. Carotenoids were co-extracted in a significant amount, although the content in the various oils was quite different.