Figures (7)  Tables (2)

    • Figure 1. 

      Effect of stunning methods on preslaughter stress of pigs. (a) Cortisol content in serum, (b) lactate content in serum. ***, p < 0.001.

    • Figure 2. 

      Effect of stunning methods on pork quality. (a) pH, (b) shear force at 24 h, (c) drip loss, (d) cooking loss. *, p < 0.05, ***, p < 0.001.

    • Figure 3. 

      Effect of stunning methods on muscle fiber structure. (a) HE staining images, (b) intercellular space of HE staining, (c) MFI at postmortem 24 h.

    • Figure 4. 

      Effect of stunning methods on postmortem energy metabolism of skeletal muscle cells. (a) Lactate, (b) glycogen, (c) ATP. *, p < 0.05, **, p < 0.01, ***, p < 0.001.

    • Figure 5. 

      Effect of stunning method on cell death. (a) TUNEL staining images, (b) Western blotting images of MLKL and phosphor-MLKL, (c) MLKL phosphorylation level, (d) caspase-3 activity. *, p < 0.05, ***, p < 0.001.

    • Figure 6. 

      Effect of ATP treatment on the meat quality of electrically stunned pork. (a) pH, (b) shear force at 24 h, (c) glycogen content, (d) lactate content, (e) intercellular space of HE staining, (f) MFI at 24 h, (g) HE staining. *, p < 0.05, **, p < 0.01; ***, p < 0.001.

    • Figure 7. 

      Effect of ATP treatment on skeletal muscle cell death. (a) TUNEL staining images, (b) Western blotting image of MLKL and phosphor-MLKL, (c) MLKL phosphorylation level, (d) caspase-3 activity. *, p < 0.05, **, p < 0.01, ***, p < 0.001.

    • Stunning method Postmortem time (h) L* a* b*
      Electrical stunning 1 45.46 ± 1.14 Ba 3.20 ± 0.66 Aa 2.12 ± 0.25 Ba
      5 47.56 ± 1.24Aab 3.97 ± 0.66 Aa 3.23 ± 0.26 Aa
      10 48.72 ± 1.16 Aa 4.09 ± 0.55 Aa 3.83 ± 0.23 Aa
      24 50.10 ± 0.72 Aa 4.73 ± 0.54 Aa 3.56 ± 0.27 Aa
      Carbon dioxide stunning 1 44.41 ± 0.36 Ba 3.02 ± 0.38 Aa 2.02 ± 0.14 Ba
      5 43.44 ± 0.30 Bb 3.23 ± 0.38 Aa 2.04 ± 0.17 Ba
      10 44.68 ± 0.62 Bb 3.09 ± 0.50 Aa 2.90 ± 0.55 Ba
      24 47.75 ± 0.38 Ab 2.77 ± 0.35 Ab 3.92 ± 0.24 Aa
      Different uppercase letters indicate significant differences in pork color at different postmortem times (p < 0.05), while different lowercase letters indicate significant differences in meat color due to different stunning methods (p < 0.05).

      Table 1. 

      The effect of electrical stunning and carbon dioxide stunning on color in pork (mean ± SE).

    • Injection Postmortem time (h) L* a* b*
      NS 0 38.02 ± 0.38Ca 6.48 ± 0.22ABa 1.07 ± 0.08Ca
      1 37.79 ± 0.53Ca 6.08 ± 0.39ABa 1.36 ± 0.06Ca
      5 40.34 ± 0.91Ba 6.98 ± 0.30Aa 2.19 ± 0.19Ba
      10 44.79 ± 0.67Aa 6.01 ± 0.30Ba 2.12 ± 0.10Bb
      24 45.39 ± 0.78Aa 6.73 ± 0.28ABa 2.89 ± 0.21Ab
      ATP 0 38.68 ± 0.35Ba 6.33 ± 0.21ABa 1.17 ± 0.06Ca
      1 39.37 ± 0.69Ba 6.23 ± 0.23ABa 1.47 ± 0.08Ca
      5 40.67 ± 0.75Ba 7.26 ± 0.59Aa 2.55 ± 0.10Ba
      10 43.49 ± 0.83Aa 5.48 ± 0.35Ba 2.75 ± 0.15Ba
      24 44.66 ± 0.85Aa 5.94 ± 0.37Ba 3.53 ± 0.11Aa
      Different uppercase letters indicate significant differences in pork color at different postmortem times (p < 0.05), while different lowercase letters indicate significant differences in meat color due to ATP treatment (p < 0.05).

      Table 2. 

      Effect of ATP treatment on color in electrically stunned pork (mean ± SE).