Effects of high-pressure processing on proteolytic enzymes and proteins in cold-smoked salmon during refrigerated storage

The present paper describes the effects of high-pressure processing on the activity of proteolytic enzymes in cold-smoked salmon and enzyme extracts for pressures up to 300 MPa. The activities of the three enzymes, cathepsin B-like, cathepsin B + L-like and calpains were reduced at all pressure levels of up to 300 MPa (at ca. 9 °C for 20 min) in crude enzyme extracts prepared from cold-smoked salmon. Calpain almost completely inactivated at 300 MPa. High-pressure did not influence general proteolytic activity but activated the enzymes in muscles at higher pressure levels studied until 18 days of storage. An increase in the activity of cathepsin B + L-like and calpain was seen after 12 days of refrigerated storage. Myosin heavy chain was less affected at higher pressure levels (300 MPa) only as shown by Sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) of proteins and further refrigerated storage had no obvious effects on proteins.