PUFAs in Fish: Extraction, Fractionation, Importance in Health

Polyunsaturated fatty acids (PUFAs), especially eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), are currently in demand in the pure form and actively being studied to understand their potential roles in human health. Arachidonic acid, 20:4 (n-6), and DHA, 22:6 (n-3), are important in normal neurodevelopment and visual function. Infants fed formula often have low blood lipid 20:4 (n-6) and 22:6 (n-3). Consumption of fish oils may increase the 20:5 (n-3) (EPA) and 22:6 (n-3) (DHA) in human blood. Some marine fish oils contain higher amounts of arachidonic acid, EPA, and DHA. PUFA contents in different marine fishes and methods for their extraction and fractionation, in terms of fatty acid constituents in the form of methyl esters, are covered in this review. Emphasis is given to the fractionations of EPA and DHA by means of supercritical fluid extractions (SFE). The advantages of SFE compared to conventional methods are discussed in this review. PUFAs are usually extracted at about 10 to 30 MPa and at 40 to 80 degrees C. SFE is a promising and currently the best technique to extract PUFAs, especially EPA and DHA, from marine and freshwater fish.