RELATIONSHIP OF MYOFIBRIL FRAGMENTATION INDEX TO MEASURES OF BEEFSTEAK TENDERNESS

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Abstract
Samples were removed from 6 veal, 35 A‐maturity and 12 C‐maturity bovine longissimus (L) muscles at 1 and 7 days postmortem. Myofibril fragmentation index (MFI), Warner‐Bratzler (W‐B) shear‐force, sensory panel evaluation and sodium dodecyl sulfate (SDS) polyacrylamide gels of myofibrils were determined on muscle samples and steaks. Correlation coefficients between MFI and W‐B shear‐force were ‐0.95, ‐0.73 and ‐0.65 and, between MFI and sensory tenderness, were 0.97, 0.75 and 0.72 for steaks postmortem aged for 7 days at 2°C from veal, A‐maturity and C‐maturity carcasses, respectively. SDS‐polyacrylamide gels showed that the intensity of the 30,000‐dalton component corresponded to the tenderness level of the steaks. These results demonstrate that MFI accounts for about 50% of the variation in tenderness and that myofibril fragmentation and the intensity of the 30,000‐dalton component offer potential usefulness as indices of tenderness.