Effects of different packaging atmospheres and injection-enhancement on beef tenderness, sensory attributes, desmin degradation, and display color.

The objectives were to determine the effects of packaging atmosphere and injection-enhancement on tenderness, sensory traits, desmin degradation, and display color of different beef muscles. Longissimus lumborum (LL; n = 12 pairs), semitendinosus (ST; n = 12 pairs), and triceps brachii (TB; n = 24 pairs; 12 from the same carcasses as the LL and ST and 12 additional pairs) were obtained from the same USDA Select, A-maturity carcasses. On d 7 postmortem, each muscle from one side of the carcass was injection-enhanced, and each muscle from the other side was nonenhanced. Steaks 2.54-cm thick were cut from the muscles and packaged in vacuum packaging (VP), ultra-low oxygen with CO (ULO(2)CO; 0.4% CO/35% CO(2)/69.6% N(2)) modified atmosphere packaging (MAP), or high-oxygen MAP (HiO(2); 80% O(2)/20% CO(2)) and assigned to 14-d tenderness or display followed by 18- or 28-d tenderness measurement. Steaks packaged in HiO(2) MAP were in dark storage (2 degrees C) for 4 d and all other steaks for 14 d. Steaks for Warner-Bratzler shear force, sensory panel (n = 8 trained panelists), and desmin degradation were cooked to 70 degrees C. Steaks were displayed under fluorescent lighting (2,153 lx, 3,000 K) for 7 d. Trained color panelists (n = 10) assigned display color scores. Enhanced steaks had lower (P < 0.05) Warner-Bratzler shear force values than nonenhanced steaks. Sensory panelists found that nonenhanced steaks packaged in ULO(2)CO MAP or VP were more tender (P < 0.05), had more (P < 0.05) beef flavor, and had less (P < 0.05) off-flavors than steaks packaged in HiO(2) MAP. The LL and TB were more tender (P < 0.05) according to myofibrillar tenderness than the ST. Nonenhanced steaks were less (P < 0.05) juicy than enhanced steaks. The most common off-flavors associated with steaks packaged in HiO(2) MAP were oxidative or rancid. Enhanced steaks had more (P < 0.05) off-flavors than nonenhanced steaks, with typical descriptors of salty, metallic, or chemical, in addition to an undesirable mushy texture. Desmin degradation increased (P < 0.05) from 7 to 14 d postmortem and differed among muscles but was not affected (P > 0.05) by packaging or enhancement. Enhanced steaks were darker (P < 0.05) initially than nonenhanced steaks. Steaks packaged in HiO(2) MAP discolored faster (P < 0.05) and to a greater extent (P < 0.05) than steaks packaged in VP or ULO(2)CO MAP. Nonenhanced muscles packaged in VP and ULO(2)CO MAP had more stable display color and very desirable tenderness and flavor compared with those packaged in HiO(2) MAP.