Effects of cations on the “salt in” of myofibrillar proteins

•Salt is a key ingredient to control the functionalities of myofibrillar proteins.•Salt influences the solubilities and zeta potentials of myofibrillar proteins.•“Salt in” of MPs is more affected by the cations with higher degree of hydration.•No evidence of increased electrostatic interaction was found during “salt in”.•Highly hydrated anions may interfere with the “salt in” effect of cations.

The solubilities of myofibrillar proteins (MPs) increased monotonically with increasing NaCl concentration at pH = pI (isoelectric point), but decreased monotonically with increasing NaCl concentration at pH < pI. At pH > pI, the solubilities decreased initially, but increased with increasing NaCl concentrations from 0.2 to 0.8 M. For chloride salts, the “salt in” effect of cations decreased in the order: Li+ > Na+ > K+ > Rb+. For sodium salts, the “salt in” effect of anions decreased in the sequence: Cl¯ > Br¯ > I¯ > SCN¯. The “salt in” effect of cations were stronger than that of anions. No evidence of increased electrostatic interaction was found during “salt in”. Presence of CH3COO¯ decreased the solubilization effect of Na+. These results indicate the “salt in” of MPs is more affected by the cations with higher degree of hydration, which may be interfered by the presence of highly hydrated anions.

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