Effects of ultra-high pressure treatment on the protein denaturation and water properties of red swamp crayfish (Procambarus clarkia)

This study aimed at understanding the effects of ultra-high pressure (UHP) treatment on the quality, protein structure and water distribution of red swamp crayfish. After pressurization (100–500 MPa, 5 min), shear force, sulfhydryl (total and reactive) and carbonyl content of myofibrillar protein extracted from crayfish muscle were significantly increased (P < 0.05) with the elevated pressure, while salt soluble protein content and Ca2+-ATPase activity decreased (P < 0.05), and the secondary structure was not affected by the pressure level. After pressurization at 300 MPa, the Ca2+-ATPase activity decreased by 0.65 fold comparing with the control (P < 0.05), while the shear force, drip loss, total and reactive sulfhydryl and carbonyl content increased by 0.34, 0.32, 0.36, 0.36 and 1.56 fold, respectively (P < 0.05). Besides, SDS-PAGE of percolate displayed the decrease of actin band (42 kDa) intensity and appearance of new bands (25–40 kDa) at 300 MPa. The increased T21 (immobilized water) and T22 (free water) of samples treated at high pressure (below 400 MPa) suggested the redistribution of water compartments, which was further confirmed with the images of proton compartments. Overall, moderate UHP treatments (less than 300 MPa) could be applied to modify the protein structure and water distribution of crayfish muscle.