Origin of high-pressure induced changes in the properties of reduced-sodium chicken myofibrillar protein gels containing CaCl2: Physicochemical and molecular modification perspectives.

The improvement mechanism of high pressure processing (HPP, 100-300 MPa, 10 min) on the gelation properties of reduced-sodium (0.3 M sodium chloride) myofibrillar protein containing 20 mM CaCl2 (MP-Ca) were explored. The results showed that the water holding capacity (WHC) and strength of MP-Ca gel reached the maximum values under 200 MPa. This was attributed to substantial solubilization of myosin heavy chain and actin, a decreased protein aggregation ability and the exposure of both tyrosine and tryptophan residues resulting from the unfolding of the protein tertiary structure. However, 300 MPa induced the hydrophobic rearrangement of MP and the disulfide cross-linking of the myosin S-1 subfragment, leading to the formation of large protein aggregates and decreased solubility of MP, thus resulting in a weaker gel with a reduced WHC. Therefore, moderate HPP (approximately 200 MPa) and low concentrations of CaCl2 could potentially improve the gelation properties of reduced-sodium meat products.