Effect of sodium bicarbonate and sodium chloride on aggregation and conformation of pork myofibrillar protein

Abstract

To investigate the effect of sodium bicarbonate instead of sodium chloride, the changes in pH, turbidity, aggregation, and conformation of myofibrillar protein solution with various amounts of sodium chloride and sodium bicarbonate were studied. When the sodium bicarbonate was increased from 0% to 0.4%, accompanied by the sodium chloride being decreased from 2.0% to 0.8%, the pH increased about 1.20 unites; the absolute values of the Zeta potential, active sulfhydryl, and surface hydrophobicity increased significantly (p < 0.05); and the turbidity, particle size, and Ca²⁺-ATPase activity decreased significantly (p < 0.05). In addition, the Mg²⁺-ATPase activity was not significantly different (p > 0.05) when increasing sodium bicarbonate, implying that sodium bicarbonate did not affect the actin. Overall, the results indicated that an increase in sodium bicarbonate could improve solubility, expose more hydrophobic residues and sulfhydryl groups, and induce Ca²⁺-ATPase inactivation and protein unfolding, leading the myofibrillar protein to denaturation easily.

Keywords: Ca(2+)-ATPase; Hydrophobic; Myofibrillar protein; Sodium bicarbonate; Sodium chloride.