Optimization of oil extraction from Nannochloropsis salina biomass paste

A 1-step extraction process is reported for near quantitative (> 96%) extraction of the total lipids from the biomass paste (~ 72% moisture by weight) of the marine microalga Nannochloropsis salina. The composition of the solvent mixture of chloroform, methanol and water is first optimized for a near quantitative extraction of the lipids. The optimal solvent mixture is found to be chloroform, methanol and water in the volume ratio of 5.7:3:1. This solvent composition is then used in a 1-step extraction process to optimize the extraction time, temperature and the volume of the solvent mixture required for extraction from 1 g dry equivalent of the biomass paste. The optimal extraction conditions are found to be 25 °C in a 2-h extraction process using 33 mL of the solvent mixture. Compared to the commonly used Bligh and Dyer extraction protocol, the proposed 1-step extraction reduced the mixed solvent use by ~ 48% and the extraction time by ~ 78%.