Comparison of protease properties from skipjack tuna viscera after defatting by supercritical carbon dioxide and organic solvent

摘要

The characterization of protease from tuna viscera were carried out after lipid extraction by supercritical carbon dioxide (SCO_2) and organic solvents, n-hexane. Supercritical extraction process for lipid isolation was performed at different temperatures (35-45°C) and pressures (15-25 MPa) for 2.5 h. The mass flow rate of carbon dioxide was 22g/min entire the extraction process. The amount of oil extracted by SCO_2 was increased with the temperature and pressure. The highest oil extracted residues of tuna viscera were used for characterization of protease. The organic solvent treated residue of tuna viscera showed higher enzyme activity than that of SCO_2 treated residue. The crude extracts of SCO_2 and n-hexane treated tuna viscera retained the almost similar optimum pH and pH stability for protease. The optimum temperature for protease was also same in both the crude extracts of SCO_2 and n-hexane treated tuna viscera. But thermal stability was slightly higher in SCO_2 treated residue comparing to n-hexane treated residue of tuna viscera. The crude extracts of untreated and SCO_2 and n-hexane treated tuna viscera showed no differences in protein pattern at SDS-PAGE.