Daily Quantification of Myoglobin Forms on Beef Longissimus Lumborum Steaks Over 7 Days of Display by Near-infrared Diffuse Reflectance Spectroscopy

Near-infrared diffuse reflectance spectroscopy (NIR-DRS) was utilized to develop an algorithm using approximately 18 wavelengths spanning 480 to 650 nm to determine oxymyoglobin (OxyMb), deoxymyoglobin (DeoxyMb), and metmyoglobin (MetMb) contents on beef longissimus lumborum muscles. Daily changes in subsurface myoglobin redox forms were evaluated for 7 d using NIR-DRS and compared with the surface color as assessed by a HunterLab MiniScan spectrophotometer as a reference modality. Both measurements revealed that MetMb increased steadily over the duration of display, showing high correlation (R2 = 0.91) between the 2 methods. Comparatively, whereas NIR-DRS revealed OxyMb to have decreased steadily over the period of display, the HunterLab MiniScan spectrophotometer indicated a much later onset of the apparent decrease of OxyMb, resulting in a moderate correlation (R2 = 0.64) between the 2 methods. No correlation was found between the 2 methods regarding the changes of DeoxyMb over the duration of display. The newly developed NIR-DRS algorithm has potential as an alternative method of color assessment in postrigor skeletal muscle.