Investigation of mechanisms by which sodium citrate reduces the pink color defect in cooked ground turkey

The principal mechanism by which sodium citrate reduces the pink color defect in cooked ground turkey was investigated. Sodium citrate (SC; 0, 0.125, 0.25, 0.5, 1.0, 2.0 M), sodium nitrite (0.01, 0.1 M), and nicotinamide (0.5, 0.75 M) were combined in solutions of bovine hemin to determine SCs ability to bind heme iron and competitively inhibit pink-color-generating ligands from binding. Additionally, the effects of sodium erythorbate (0, 275, 550 ppm), ferrous iron chloride (0, 0.3, 3.0, 30 ppm), and ferric iron chloride (0, 0.3, 3.0, 30 ppm) on SCs ability to reduce pink cooked color was examined. Absorbance curves of hemin + nitrite and hemin + nicotinamide were relatively unaffected by SC, therefore whether or not SC bound heme iron, that did not appear to be a mechanism for inhibiting the pink color defect. Both ferrous and ferric iron chloride had minimal effects on color values, possibly due to sodium tripolyphosphate chelation ability in the meat system and thus their presence did not enhance SCs ability to reduce the pink color defect. However, sodium erythorbate, a reducing agent, inhibited SCs ability to decrease the pink color defect in samples induced pink with sodium nitrite and nicotinamide. Therefore, it appears SC requires the presence of oxygen and may participate in oxidative processes to reduce the pink color defect.