Abstract: To investigate the coexistence of PSE (pale, soft, and exudative) and normal meat within the longissimus dorsi muscle from the same pig, as well as the cause of the associated quality differences, this study comparatively analyzed the eating quality, glycolytic metabolism, myofibrillar protein structure, and microstructural characteristics of different regions of normal, classical PSE, and PSE heterogeneous longissimus dorsi. The results showed that the PSE-like zone (YQP) of PSE heterogeneous meat had significantly lower pH than the normal anterior zone (YQN), while the brightness value, centrifugal loss rate, and shear force were significantly higher than those in YQN (P < 0.05). Glycogen content was significantly lower, and lactate content was significantly higher in YQP than in YQN (P < 0.05). YQP and the anterior region of classical PSE meat (PQ), as well as YQN and the anterior region of normal meat (NQ), exhibited similar eating quality traits, with no significant differences in glycogen or lactate content. Compared with YQN, YQP showed increased carbonyl content and decreased total sulfhydryl content, accompanied by smaller muscle fiber diameter and higher density. In addition, no significant differences were observed between the middle and posterior regions of PSE heterogeneous meat and the corresponding regions of normal meat, nor were there any significant differences between the different regions of classical PSE meat and the corresponding regions of normal meat. In conclusion, protein oxidative denaturation and disruption of myofibrillar structure caused by localized abnormal glycolytic metabolism contribute to the quality differences observed in the anterior region of PSE heterogeneous meat.

Key words: porcine longissimus dorsi; PSE (pale, soft, and exudative) meat; heterogeneous distribution; glycolysis; quality differences