The impact of ultimate pH on muscle characteristics and sensory attributes of the longissimus thoracis within the dark cutting (Canada B4) beef carcass grade

• Dark cutting carcasses were identified that had m. longissimus thoracis pH less than 6.0.
• Dark cutting carcasses with pH values less than 6.0 produced tough beef.
• Causal mechanisms of DFD carcasses with pH less than 6.0 may be different from typical DFD carcasses.

Canada B4 beef carcasses are penalized because the longissimus thoracis (LT) at the grade site (12–13th ribs) is darker than the color threshold for normal bright cherry-red beef. Previous studies have shown that not all B4 carcasses have pH > 6.0; therefore, the relationship between LT pH and meat quality was investigated by collecting thirty half-carcasses comprised of the following: ten Canada AA (AA, control), ten B4 with LT pH > 6.0 (CL, classic), and ten B4 with LT pH < 6.0 (AT, atypical). LT from CL carcasses had the lowest mean lactate level, lowest glucidic potential and highest mean pH value. LT muscle from CL and AT carcasses was dark and had decreased purge, drip loss and cooking loss. Warner–Bratzler shear force values and sensory panel results showed that AT beef was toughest (P < 0.0001), substantiating economic penalty. Causal mechanisms for AT carcasses may be inconsistent with traditional DFD theory because of close to normal final muscle pH.