3. Results and discussion
3.1. Instrumental color and biochemical attributes
Myoglobin concentration was not different (P N 0.05) between ISM
(6.50 ± 0.18 mg/g) and OSM (6.39 ± 0.15 mg/g) on day 0. In support,
Sammel, Hunt, Kropf, Hachmeister, Johnson (2002) also reported
similarmyoglobin concentration in ISMand OSMprior to retail display.
On day 0 of retail display, ISMsteaks demonstrated (P b 0.05) greater
redness (a* values) than OSMcounterparts (Fig. 1). However, the trend
reversed during retail display with OSM exhibiting greater (P b 0.05)
redness on days 2 and 4. Nevertheless, a* values decreased in both
ISM and OSM during retail display. In agreement with our data,
Sammel, Hunt, Kropf, Hachmeister, Johnson (2002) reported similar
observations on a* values of beef semimembranosus during display
under aerobic packaging; ISM exhibited greater a* values on day 0,
whereas OSM exhibited greater a* values from day 1 to day 5. Furthermore,
these authors observed lower oxygen consumption rate in ISM
than in OSM, which could have resulted in deeper oxygen penetration
into the muscle resulting in improved bloom and uniform cherry-red
color. Sawyer et al. (2007) examined intramuscular variations in the
color stability of beef semimembranosus quadrants (divided based on
cranial–caudal and proximal–distal axes; the distal quadrants represented
OSM, whereas proximal ones represented ISM). These authors
reported no difference in a* values between the four quadrants on day