Differential Abundance of Mitochondrial Proteome Influences the Color Stability of Beef Longissimus Lumborum and Psoas Major Muscles

Mitochondrial functionality affects muscle-specific beef color stability. Nonetheless, the relationship between mitochondrial proteome and muscle-specific beef color stability is yet to be examined. Therefore, the objective of the present study was to differentiate the proteomes of mitochondria from beef longissimus lumborum (LL; color-stable muscle) and psoas major (PM; color-labile muscle) steaks during retail display. LL and PM muscles from 7 beef carcasses (USDA Choice; 48 h postmortem) were fabricated into 1.92-cm-thick steaks and were aerobically packaged and retail displayed for 6 d. Mitochondria were isolated on day 3 and 6, whereas instrumental color and biochemical attributes were evaluated on day 0, 3, and 6. Mitochondrial proteome was analyzed employing two-dimensional electrophoresis. The protein spots exhibiting 1.5-fold or more intensity differences (P < 0.05) between the muscles and display days were subjected to tryptic digestion and identified by tandem mass spectrometry. Whereas color stability decreased in both muscles during retail display, LL steaks demonstrated greater (P < 0.05) color stability during display than their PM counterparts. Mitochondria could not be isolated from PM steaks on day 6 because of extensive degradation. Seven proteins were differ-entially abundant (P < 0.05) in LL and PM on day 3 of display. In LL steaks, 7 proteins were more abundant (P < 0.05) on day 3 than on day 6 of retail display. The differentially abundant proteins were enzymes, binding proteins, and proteins involved in biosynthesis. These results indicated that differential abundance of mitochondrial proteome could also contribute to the variations in color stability of beef LL and PM muscles during retail display.