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In order to investigate the regulatory effect of B-cell lymphoma-2 (Bcl-2) on cell apoptosis and water retention in postmortem Qinchuan beef, the longissimus dorsi muscle of Qinchuan cattle was injected with either 200 μmol/L glycochenodeoxycholic acid (GCDA) or 10 μmol/L 2-ethyl-3-methylpentanamide (ABT-737) solution and aged at 4 ℃ postmortem. After 0, 6, 12, 24, 48, 72 and 120 h, the changes in Bcl-2 and Bcl-2-associated X protein (Bax) contents, the concentrations of endoplasmic reticulum and mitochondrial calcium ion, voltage-dependent anion channel protein 1 (VDAC1) expression, calpain content, the mitochondrial apoptosis pathway and water retention were determined. The results showed that at 6 h after slaughter, the Bcl-2 content of the GCDA-treated group was significantly higher than that of the control group (P < 0.01), the calcium ion concentration in the endoplasmic reticulum was significantly lower than that of the control group (P < 0.01), and cooking loss was significantly lower in both treatment groups than the control group (P < 0.05). At 12 and 24 h post-slaughter, the Bcl-2 content of the ABT-737-treated group was significantly lower than that of the control group (P < 0.01). At 12 and 120 h post-slaughter, the endoplasmic reticulum calcium ion, mitochondrial calcium ion and calpain levels in the ABT-737-treated group were significantly greater than those in the control group (P < 0.01). During 0–120 h post-slaughter, the total expression of VDAC1 in both treatment groups was lower than that in the control group. In summary, during the postmortem aging of Qinchuan beef, under the regulation of Bcl-2, calcium overload occurs through VDAC1-facilitated calcium transport, resulting in the activation of calpain, and the overloading of Ca2+ in mitochondria promotes the activation of caspase-9 and caspase-3, thus inducing cell apoptosis. The higher the degrees of cell apoptosis and caspase activation, the higher the degree of degradation of myofibrillar proteins, and the poorer the water-holding capacity of the meat.

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To investigate the effect of basal immunoglobulin (BSG) expression during postmortem maturation on meat quality, changes in quality indicators such as pH, cooking loss and myofibril fragmentation index (MFI), as well as energy substance and BSG contents of Qinchuan cattle meat were measured after different periods (0, 2, 4, 6 and 8 days) of postmortem aging at 4 ℃. The proteomic changes were also analyzed using 4D-label free quantification (4D-LFQ). The results showed that during the postmortem storage period, the expression of BSG showed an overall trend of initially increasing and then decreasing. The levels of the energy substances ATP, ADP, AMP and NADH showed a decreasing trend; pH and cooking loss initially decreased and then increased; MFI showed a continuous increasing trend. The correlation analysis showed that the expression of BSG was significantly positively correlated with cooking loss (P < 0.01), but negatively correlated with pH, ATP and NADH levels (P < 0.05). However, it had no significant correlation with ADP or AMP contents. Therefore, the change of BSG expression in the Longissimus dorsi muscle of Qinchuan cattle during postmortem maturation was closely related to the quality and energy metabolism of beef. Proteomics identified that BSG and its associated differential proteins had catalytic activity, hydrolase activity and proton-transporting ATP synthase activity, bound to ATP, ribonucleotides and carbohydrate derivatives in cells, and were involved in the regulation of molecular functions and hydrogen ion transport across membranes. These biological effects caused mitochondrial damage and were involved in changes in meat tenderness through energy metabolism.

Copyright of Shipin Kexue/ Food Science is the property of Food Science Editorial Department and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)