Effects of tartrate on color stability and myoglobin affinity for oxygen in beef.

The effects of the affinity of myoglobin for oxygen on meat discoloration were investigated. First, we showed that 10 mmol/L tartrate significantly decreased the deoxygenation rate in vacuum-packed beef, although it did not reduce mitochondrial oxygen consumption activity. Second, the myoglobin affinity was evaluated with or without 1 mg/mL mitochondria and/or 10 mmol/L tartrate. The oxygen concentration that gives 50 % of the deoxygenation ratio was evaluated as myoglobin affinity. The affinity in the "with mitochondria" condition (0.370 ± 0.006 %) was significantly lower than that of "myoglobin" (0.312 ± 0.019 %), "with tartrate" (0.292 ± 0.009 %), and "with mitochondria and tartrate" (0.287 ± 0.022 %). Furthermore, the effect of 10 mmol/L tartrate on the myoglobin oxidation rate in beef was observed at 0.18-4.2 % oxygen. The addition of tartrate inhibited oxidation at lower concentrations but promoted oxidation at higher concentrations, with 1 % being the divergent concentration. Using tartrate, we demonstrated that myoglobin affinity is a determining factor for the oxygen concentrations that promote beef discoloration.