COMPARISON BETWEEN EXTRACTION OF LIPIDS AND FATTY-ACIDS FROM MICROALGAL BIOMASS

Seven solvent mixtures have been used to extract the lipid fraction of lyophilized biomass of Isochrysis galbana. Six of them were composed of biocompatible solvents. Each method was carried out under relaxed o perating conditions (i.e., one hour at room temperature) with extracti on in a nitrogen atmosphere to prevent autooxidation and degradation o f polyunsaturated fatty acids (PUFAs). Apart from the well-established Bligh and Dyer method [Can. J. Biochem. Physiol 37:911 (1959)] (Cl3CH /MeOH/H2O, 1:2:0.8, vol/vol/vol), which rendered the highest yield of lipids (93.8%), ethanol (96%) and hexanelethanol (96%), 1:2.5 vo/vol p roduced the best results (84.4 and 79.6%, respectively). To obtain fre e fatty acids, KOB was added to the solvent mixtures used to extract t he total lipids, except for Cl3CH/MeOH/H2O, and direct saponification was carried out at 60 degrees C for 1 h or at room temperature for 8 h . The highest yields obtained by direct saponification were 81% with h exanelethanol (96%), 1:2.5, vol/vol and 79.8% with ethanol (96%). Part ial yields of the main n-3 PUFAs found in I. galbana, stearidonic acid (SA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), wer e calculated for both extraction methods. For lipid extraction with et hanol (96%), yields of 91, 82 and 83% were obtained for SA, EPA and DH A, respectively. When direct saponification was used, hexanelethanol ( 96%; 1:2.5, vol/vol) produced the best yields of (91, 79 and 69% for S A, EPA and DHA, respectively).