Enzymatic hydrolysis of phospholipids from Isochrysis galbana for docosahexaenoic acid enrichment

This paper describes the use of lipases for the production of a lipid fraction rich in docosahexaenoic acid (DHA) using phospholipids from the microalga Isochrysis galbana as raw material. Fatty acid compositions of total lipids and lipid classes of I. galbana were studied. DHA accounted for 13.5% of total fatty acids. However, the DHA content of the phospholipid fraction was 50% and 75% of total DHA was carried by phospholipids, mainly at the sn-2 position. These phospholipids contained neither eicosapentaenoic acid nor arachidonic acid. Selective phospholipid hydrolysis using 12 lipase preparations has been studied in order to produce lipid fractions enriched in DHA. Five lipases showed discrimination between DHA and other fatty acids. A lipid fraction containing 80% of DHA was obtained with two lipases. Even though both preparations were equivalent in terms of DHA enrichment (1.5–1.6), lipase from Rhizopus oryzae gave better results as far as DHA recovery (85%) is concerned. Lipase from Mucor javanicus gave a slightly lower recovery yield (71%) for the same reaction time (3 h).