The Effects of Beef Muscle Variety on Beef Aging Indices

In order to investigate the effects of muscle variety on the indices of beef aging, 4 muscles in shoulder clods from 4 carcasses of Holstein steers obtained at 4 days postmortem were stored for 7, 14, 21 and 28 days at 0°C. The 4 muscles were Triceps brachii (TB), Supraspinatus (SS), Biceps brachii (BB) and Brachialis (BA) muscles. Sensory tenderness, shear force value (SFV), ATP-related compounds, myofibrillar fragmentation index (MFI), 30, 000 dalton component (30kDa) and collagen content were determined for each muscle. Muscles were ranked in order of the amount of collagen: BA>BB>SS>TB. The rate of increase in MFI during storage was considerably slower in the BB and BA, which contained a higher concentration of collagen, than in the TB and SS muscles. The concentration of 30kDa showed a greater increase in those muscles (TB, SS) in which myofibrillar fragmentation proceeds earlier. However, the concentration of 30kDa in those muscles was much lower than in loins as reported previously8). The pattern of changes in ATP-related compounds during storage was almost the same in every muscle and did not correspond to the differences in tenderization among muscles. In comparison with the changes in ATP-related compounds, those of SFV, MFI and 30kDa corresponded relatively well to the results of sensory tenderness. Therefore, we consider that SFV, MFI and 30kDa are more useful than ATP-related compounds as indices of aging.