Myofibrillar protein marination model: a calculation and its mechanism

The classic diffusion equation $D_e=\frac{\mathrm{RT}}{6\pi r\mathrm{\eta N}}$ and that for osmotic pressure $\pi =\beta n\mathrm{RT}$ use ion solution, but cannot be applied in a complex food system. The diffusion coefficient (D_e) is a physical quantity that describes the rate at which a substance diffuses in another medium and is commonly used in diffusion equations. Osmotic pressure (π) refers to the pressure generated when solute molecules in a solution diffuse through a semipermeable membrane toward the solvent side. Myofibrillar protein (MP), a main component in salted meat, was investigated in this study.

The results showed that, D_e values in ion solution were always higher (4.00-5.69 × 10^-10 m² s^-1) than those in MP (1.33-1.81 × 10^-11 m² s^-1), but the declining rate was slower at a salt concentration of 40-80 g kg^-1 and quicker at 80-160 g kg^-1. π_MP (2.84 MPa) was higher than π_ion (2.68 MPa) only at low contents of salt. When the salt concentration exceeded 40 g kg^-1, π_MP was lower than π_ion; π_MP increased from 2.84 to 10.08 MPa and π_ion increased from 2.68 to 10.40 MPa.

Under low contents of salt, solubility increased and α-helix decreased, resulting in partial unfolding of the protein and enhanced binding to and absorption of water. This made the viscosity decrease, thus reducing the declining rate of D_e and decreasing π_MP. At high contents of salt, aggregation increased viscosity, and thus increased the declining rate of D_e and π_MP. This would provide a theoretical foundation for the amendment of the classic equations of D_e and π_MP. © 2025 Society of Chemical Industry.