Effect of ultimate pH on the physicochemical and biochemical characteristics of turkey breast muscle showing normal rate of postmortem pH fall.

This experiment aimed to study the effect of ultimate pH (pH(u)) on the biochemical and physicochemical characteristics of turkey breast muscle with normal rate of postmortem pH fall. Five hundred turkey toms (12 wk old, 10 kg live weight) were randomly chosen from a commercial flock. At 24 h postmortem, 64 birds were randomly selected within the subgroup showing pH higher than 6.0 at 20 min postmortem and pH(u) lower than 6.1. These pH levels were used to exclude pale, soft, and exudative (PSE) meat and dark, firm, and dry (DFD) meat, respectively. The pH(u) was significantly correlated with luminance (L*; r = -0.37) and yellowness (b*; r = -0.36) at 24 h postmortem, drip losses (r = -0.56 to -0.62), thawing loss (r = -0.47), 80% compression (r = -0.29), yield of curing and cooking (r = 0.37), glycolytic potential at slaughter (r = -0.44) and lactate at 24 h postmortem (r = -0.47). Significant correlations were found between drip losses and compression test on cooked meat (r = 0.27 to 0.34). Cooking loss was correlated with WB shear force (r = 0.32). These results show that when PSE defects are excluded, the intensities of the correlations between pH(u) and meat quality traits are lower than those usually reported. The present data also indicate that the level of glycogen at time of slaughter poorly explains the variability in pH(u). Thus, further research is needed to identify the mechanisms explaining pH(u) variation in poultry muscle.