Effect of Iron Form, Temperature, and Inoculation with Clostridium botulinum Spores on Residual Nitrite in Meat and Model Systems

The effect of iron form (ferrous, ferric, heme), temperature and botulinal spores on nitrite level was determined in meat. In model systems, ferritin iron was also included, and ascorbate was used as a reducing agent. Reduced hemoglobin caused the most rapid nitrite depletion in both systems. Ferrous iron caused faster nitrite depletion in model systems than in meat. Ferrous iron reduced nitrite readily in model systems at 27°C, but not at 5°C. Ferritin iron did not affect nitrite level. In meat at 27°C, nitrite depletion was much faster in inoculated samples. Protein-bound nitrite levels were higher in meat with added ionic iron. In cured meat with added ionic iron, iron-NO-protein complexes may form, lowering the amount of nitric oxide (NO) available to inhibit botulinal spore outgrowth.