Updated publication reference for PubMed record(s): 32775575. Bovine longissimus lumborum (LL) and psoas major (PM) muscles biopsy samples were collected from four carcasses (n = 4) at 45 min, 12 h, and 36 h postmortem from a commercial beef processing facility. Proteome profile variation between beef LL and PM during the early postmortem period were evaluated by tandem mass tag labeling containing ten different isobaric compounds.