Extent of dark-cutting in beef carcasses graded Canada B4


Bruce, H.L., Holdstock, J., Uttaro, B.E., Larsen, I.L., Aalhus, J.L. (2021). Extent of dark-cutting in beef carcasses graded Canada B4. Meat Science, [online] 172 http://dx.doi.org/10.1016/j.meatsci.2020.108363

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In Canada, beef carcasses with subjectively-assessed dark meat colour at the ribeye grading site are downgraded. Thus, the condition of this single muscle reduces the monetary value of the whole carcass. To determine if muscles other than the ribeye are affected on carcasses graded as dark cutting, and if so, to what extent, this study looked at 12 other muscles in the same carcasses, using the ribeye pH to group types of dark cutting carcasses: atypical (pH < 5.8), borderline (5.8 < pH < 6.0), and classic ( pH > 6.0). Moisture loss, colour, and colour stability were tracked over 4 d of retail display. It was found that characteristics of all forequarter muscles in all pH groups were the same as those from normal carcasses and that most of the hindquarter muscles in the atypical group were as colour stable as the same muscles from normal carcasses. This showed that forequarter and hindquarter muscles from dark cutting carcasses were undervalued. A possible way of recovering some value would be to sort the atypical carcasses out from the general group of dark cutting carcasses, based either on pH or on instrumental colour.


Recovering value from dark cutting carcasses (Canada B4) was investigated by examining twelve muscles in the loin, fore- and hindquarters of atypical (AT, pH < 5.8), borderline (BD, 5.8 < pH < 6.0) and classic (CL, pH > 6.0) dark cutting carcasses. Subjective and objective colour, purge loss, and colour stability were measured over 4 days of retail display. Forequarter muscles from all dark cutting carcasses were not different from those of normal Canada AA carcasses, suggesting that forequarter muscles may be preferentially harvested for sale through normal retail outlets. None of the adductor, biceps femoris, gluteus medius, and semitendinosus muscles in the AT carcasses were dark and all had retail display colour stability comparable to that of normal steaks, indicating that these muscles in these carcasses are undervalued. Sorting of dark cutting carcasses by longissimus thoracis pH or a* and b* values will allow for value to be recovered from atypical dark cutting carcasses.

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