The effect of mechanically separated turkey (MST), ascorbate, and vacuum packaging on rates of lipid oxidation in chicken doner kebab during storage at 4 degreesC or -20 degreesC was investigated. MST and MST/ascorbate accelerated lipid oxidation compared to control kebab. Ascorbate application. and vacuum packaging inhibited lipid oxidation. The antioxidative effect of ascorbate in the absence of MST was converted to a pro-oxidative effect in the presence of MST. This suggests that the excess lipid hydroperoxides and iron complexes in MST were activated as lipid oxidation catalysts by ascorbate to overwhelm the ability of ascorbate to inhibit lipid oxidation at lower concentrations of hemoglobin, iron, and peroxides.