Gelation properties and thermal gelling mechanism of golden threadfin bream myosin containing CaCl2 induced by high pressure processing

The effects and mechanism of high-pressure processing (HPP) (100-500 MPa) and CaCl2 addition on golden threadfin bream myosin gel were investigated. Results for water holding capacity (WHC) and gel strength revealed the HPP at 100-300 MPa could markedly improve the gelation properties. The increase in the proportion of immobilized water with a reduction of water relaxation time indicated that Ca2+ and mild HPP pre-treatments contributed to restricting the water mobility within the gel matrix. Dynamic rheological measurements suggested that the thermal gelling ability of the pressurized myosin/Ca2+ increased at 100 MPa, but gradually decreased as the pressure further increased (100-500 MPa). Analysis of atomic force microscopy (AFM) results revealed that myosin modified by CaCl2 and 100-300 MPa HPP tended to aggregate into small subunits and spheroidal particles simultaneously with the decrease in surface roughness. Scanning electron microscopy (SEM) images showed that a compact, networked myosin/Ca2+ composite gel microstructure with regular and small cavities was formed by thin cross-linked strands under 300 MPa. Changes in molecular forces were used to explain the above results. CaCl2 and modest HPP enhanced and stabilized various molecular forces within the gel system. This study illustrated that CaCl2 and HPP processed a synergistic effect on the gelation properties of myosin gel.