The Effect of Free and Bound Iron on Lipid Peroxidation in Turkey Meat

Abstract

The effect of free ionic iron, heme pigments, and iron chelators on lipid peroxidation were determined in raw turkey meat. Fresh hand-deboned turkey breast and leg meat (without skin) or mechanically deboned turkey meat was homogenized with citrate-phosphate buffer at pH 5.0 or pH 6.5, or distilled water. Samples were prepared by adding iron (free ionic iron, 10 μg/g meat), hemoglobin (Hb), ferritin, or transferrin into the meat homogenate with or without diethylenetriaminepentaacetic acid (DTPA).The amount of analyzable iron in meat with ferritin and transferrin added was 5 to 8 ppm higher than that of the control, but the bound iron in transferrin and ferritin had little catalytic effect on lipid oxidation. The structural iron of Hb had little effect on the content of nonheme iron and had no effect on the lipid oxidation of meat. Weak iron binders (citrate and phosphate) significantly (P < .05) reduced the 2-thiobarbituric acid reactive substances (TBARS) values. The strong iron chelator DTPA was more effective antioxidant than weak iron binders and virtually eliminated the formation of TBARS in meat. It was concluded that the iron that is important in the catalysis of lipid oxidation is free ionic iron, neither the iron bound to transferrin or ferritin nor the central iron component in heme pigments.