Supercritical carbon dioxide extraction and fractionation of lipids from freeze-dried microalgae Nannochloropsis oculata and Chlorella vulgaris

This study deals with the selective extraction of neutral lipids from microalgae. We investigated the consequences of bypassing cell-wall disintegration before supercritical carbon dioxide extraction. Different operating parameters (use of co-solvent, pressure, and time) were tested on freeze-dried Chlorella vulgaris and Nannochloropsis oculata. The solid phase extraction technique (SPE) was used throughout the extraction process to assess variations in the yield of liberated neutral lipids, glycolipids, and phospholipids. Under operating conditions, 97% of neutral lipids were extracted from C. vulgaris using ethanol (10% v/v) as co-solvent. Neutral lipids from N. oculata represented most of the extracts (83%), whereas the proportion of glycolipids and phospholipids did not exceed 12.1% and 5.3%, respectively. Microscopic observation showed that cell wall integrity was maintained during the extraction process.