Effect of sodium bicarbonate and sodium chloride on protein conformation and gel properties of pork myofibrillar protein

To explore the potential of using sodium bicarbonate to take the place of sodium chloride, the changes in endogenous fluorescence, ultraviolet absorption spectrum, water holding capacity, gel properties and water distribution of pork myofibrillar protein were investigated. Because of the increase in pH and the exposure of more tryptophan and tyrosine residues with increasing sodium bicarbonate, the cooking yield and gel strength of pork myofibrillar protein significantly increased (P < 0.05), and centrifugal loss significantly decreased (P < 0.05). Meanwhile, the colour of the cooked pork myofibrillar protein was darker with increasing sodium bicarbonate, the bound water and immobile water were bound more tightly to the protein matrix, and the mobility of the water was lower, except for in the sample with 0.4 % sodium bicarbonate. Moreover, free water significantly increased (P < 0.05) when 0.4 % sodium bicarbonate was added, indicating that the mobility of the water was enhanced. Overall, the use of sodium bicarbonate could induce the protein conformation change, and improve the bond water content and texture properties of reduced-salt pork myofibrillar protein.