Sc-CO2 extraction of fish and fish by-products in the production of fish oil and enzyme

Abstract

Supercritical carbon dioxide (Sc-CO₂) 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-CO₂, 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-CO₂. Sc-CO₂ parameters, such as pressure (P), temperature (T), extraction time (t_ext), 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_ext: 20–150 min; F: 3–50 g/min) than the extraction of fish oil alone (P: 10–40 Mpa; T: 35–80 °C; t_ext: 30–360 min; F: 1–3000 g/min). The enzyme from the Sc-CO₂ 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-CO₂ 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.