Effects of NaCl partially substituted with KCl or MgCl2 on the properties, oral mastication, in vitro gastric digestion, and pepsin diffusion of myofibrillar protein gel

The effects of NaCl partially substituted by KCl, MgCl₂, and KCl/MgCl₂ on the gel characteristics, oral mastication, and in vitro gastric digestion of myofibrillar protein (MP) gel were investigated. The results indicated that partial substitution of NaCl by KCl or MgCl₂ did not cause obvious deterioration of gel properties within 30 % substitution levels. MgCl₂ substitution significantly increased the surface hydrophobicity of MP, and formed homogeneous network structure for effective limitation of moisture loss. The MgCl₂-substituted gel exhibited relatively lower viscosity and hardness for better swallowing. The high pepsin diffusivity in MgCl₂-substituted gel (59.57 ± 4.28 μm²/s, 30 %-Mg group) improved protein hydrolysis, and produced more shorter peptides due to the loose and relatively uniform structure compared to those of the gels only containing NaCl and partial KCl. Therefore, the changes of textural parameters, microstructure, and water mobility in sodium-reduced gel with different substitution levels could influence the subsequent gastric digestion characteristics.