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Description:
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Nineteen bovine muscles were removed from beef carcasses (n = 9 ) . Muscles were trimmed free of fat , cut into 2 .54 cm thick steaks , and were packaged in Styrofoam trays with polyvinylchloride overwrap . Steaks were assigned randomly to a day of retail display (0 - , 1 - , 2 - , 3 - , 4 - , or 5 -d ) . Steaks were evaluated over the course of retail display for objective measures of discoloration (metmyoglobin , oxymyoglobin , L* - , a* - , and b* -values ) , reducing ability (metmyoglobin reductase activity , resistance to induced metmyoglobin formation , and nitric oxide metmyoglobin reducing ability ) , oxygen consumption rate , oxygen penetration depth , myoglobin content , oxidative rancidity , and pH . Muscles were grouped according to objective color measures of discoloration . M . longissimus lumborum , M . longissimus thoracis , M . semitendinosus , and M . tensor fasciae latae were grouped as "high" color stability muscles , M . semimembranosus , M . rectus femoris , and M . vastus lateralis were grouped as "moderate" color stability
muscles , M . trapezius , M . gluteus medius , and M . latissimus dorsi were grouped as "intermediate" color stability muscles , M . triceps brachi - long head , M . biceps femoris ,
M . pectoralis profundus , M . adductor , M . triceps brachi - lateral head , and M . serratus ventralis were grouped as "low" color stability muscles , and M . supraspinatus , M . infraspinatus , and M . psoas major were grouped as "very low" color stability muscles . Generally , muscles of high color stability had high resistance to induced metmyoglobin formation , nitric oxide reducing ability , and oxygen penetration depth and possessed low oxygen consumption rates , myoglobin content , and oxidative rancidity . In contrast , muscles of low color stability had high metmyoglobin reductase activity , oxygen consumption rates , myoglobin content , and oxidative rancidity and low resistance to induced metmyoglobin formation , nitric oxide metmyoglobin reducing ability , and oxygen penetration depth . Data indicate that discoloration differences between muscles are related to the amount of reducing activity relative to the oxygen consumption rate . |