Effect of time of measurement on the relationship between metmyoglobin reducing activity and oxygen consumption to instrumental measures of beef longissimus color stability.

Contributions of initial and retained levels of oxygen consumption and reducing capacity to animal variation in color stability were evaluated. Instrumental color values were determined on longissimus steaks (n=257) during 6 d of display. Oxygen consumption (OC), nitric oxide metmyoglobin reduction (NORA), initial metmyoglobin formation (IMF), and post-reduction metmyoglobin (PRM) were measured on d 0 and 6. During display, color variables, OC and reducing ability decreased (P<0.05). Color stable steaks had greater (P<0.05) reducing ability on d 0 and 6 and lower (P<0.05) OC on d 0 than unstable steaks. Color change was correlated to OC, NORA, and PRM on d 0 (r=0.19, -0.44 and 0.45, respectively) and to NORA and PRM on d 6 (r=-0.50 and 0.52, respectively). These data suggest that initial capacity for OC and reducing ability, combined with retained reducing ability contribute to animal variation in color stability.