Sc-CO extraction of fish and fish by-products in the production of fish oil and enzyme.

Supercritical carbon dioxide (Sc-CO) is an alternative tool to extract lipid for the production of fish oil and enzyme from fish by-products (FBPs). In the application of Sc-CO, this review covers sample preparation, lipid extraction operation, and characterization of fish oil and enzyme as final products. Generally, the fish samples with moisture content less than 20% and particle size less than 5 mm are considered before lipid extraction with Sc-CO. Sc-CO parameters, such as pressure (P), temperature (T), extraction time (t), and flow rate (F), for simultaneous recovery of fish oil, protein, and enzyme were found to be less severe (P: 10.3-25 MPa; T: 25-45 °C, t: 20-150 min; F: 3-50 g/min) than the extraction of fish oil alone (P: 10-40 Mpa; T: 35-80 °C; t: 30-360 min; F: 1-3000 g/min). The enzyme from the Sc-CO defatted sample showed higher activity up to 45 U/mg due to lower denaturation of protein as compared to the organic solvent treated sample albeit both samples having similar pH (6-10) and temperature stability (20-60 °C). Overall, mild extraction of lipid from FBPs using Sc-CO is effective for the production of enzymes suitable in various industrial applications. Also, fish oil as a result of extraction can be produced as a health product with high polyunsaturated fatty acids (PUFAs) and low contamination of heavy metals.