No abstract

Premature browning is a condition wherein ground beef exhibits a well-done appearance before reaching the USDA recommended internal cooked meat temperature of 71.1 °C; however, the mechanism is unclear. The objectives of this study were: (1) to determine the effects of packaging and temperature on metmyoglobin reducing activity (MRA) of cooked ground beef patties and (2) to assess the effects of temperature and pH on thermal stability of NADH-dependent reductase, lactate dehydrogenase (LDH), and oxymyoglobin (OxyMb) in-vitro. Beef patties (lean: fat = 85:15) were packaged in high-oxygen modified atmosphere (HiOX-MAP) or vacuum (VP) and cooked to either 65 or 71 °C. Internal meat color and MRA of both raw and cooked patties were determined. Purified NADH-dependent reductase and LDH were used to determine the effects of pH and temperature on enzyme activity. MRA of cooked patties was temperature and packaging dependent (P < 0.05). Vacuum packaged patties cooked to 71 °C had greater (P < 0.05) MRA than HiOX-MAP counterparts. Thermal stability of OxyMb, NADH-dependent reductase, and LDH were different and pH-dependent. LDH was able to generate NADH at 84 °C; whereas NADH-dependent reductase was least stable to heat. The results suggest that patties have MRA at cooking temperatures, which can influence cooked meat color.

No abstract

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. Proteins present in the early postmortem LL and PM proteomes were identified and quantified using tandem mass tag (TMT) labelled, fractionated peptides coupled to liquid chromatography tandem mass spectrometry (LC-MS/MS). The data are supplied in this article and are related to “Tandem mass tag labeling to characterize muscle-specific proteome changes in beef during early postmortem period” by Zhai et al. [1].